The difficulty curve in the game has... problems...

[IdowhatIwant]

You vastly overestimate my ability to translate "you know where you stopped casting in order to move because you can't mouse-turn and click a cooldown at the same time, don't do that." and "you know when you stopped casting in order to process information to not wipe everyone, don't do that either" into an actual increase in performance.

Wack a dummy and move around while doing it. MCH is the best for being mobile and maintaining up time. Do your rotation enough you won't have to think about it at all itll just be muscle memory. Also practice not clicking skills and try to adjust your keybinds where you can actively press all your skills with one hand and little movement. Good keybinds are very key, I can't really give you advice on that really mine many would consider bad but its comfortable for me. May want to look up some guides on keybinding and play around with it. It took me a couple hours to figure out how I wanted mine, and that is excluding practicing it afterwards and making adjustments.

For example I have my rotation as qwe, with my ogcds gause barrel and ricochet as 12, so I can easily press 12 after each step of my rotation, Drill air anchor and chainsaw I have as rty.

[Issaella]

Wack a dummy and move around while doing it. MCH is the best for being mobile and maintaining up time. Do your rotation enough you won't have to think about it at all itll just be muscle memory. Also practice not clicking skills and try to adjust your keybinds where you can actively press all your skills with one hand and little movement.

I've been trying for 15y and in that time managed to add only 4 more hotkey slots and even then I have a tendency to mis-tap hotkeys and/or not reset my fingers to movement keys properly regardless of practice. I am at my limit in terms of hotkeys, it's just not something I can improve in that dept. So it's click some of them or don't use them at all. FF14 has so many abilities (like old WoW) that there are are simply too many for me to hotkey everything I need so it's main abilities and short cooldowns, whereas longer cooldowns I click. If I get used to the timing on boss abilities I should be able to avoid that problem (I have in Unreal/Ex1&2). It also means I'm coming into this with a major impediment that most people don't have to deal with, that was one of my major reasons for not even trying.

I only have 1 job geared out at 590+ presently, SMN, I thought about MCH, but I can't play BRD or DNC with any kind of skill. Also, with how far MCH is behind every other DPS it felt like a huge handicap, if I could get SMN even close in terms of performance it would easily out-DPS MCH. SMN also leaves the door open to playing rezmage with the same gearset if I need/want to (I'm not as good at it, but I can play it ok). It would take me a couple weeks of grinding to get another job to 590+ and that is the bare minimum I'm willing to enter this in order to stack the deck in my favor as much as I possibly can.

[Inanegrain]

I've been trying for 15y and in that time managed to add only 4 more hotkey slots and even then I have a tendency to mis-tap hotkeys and/or not reset my fingers to movement keys properly regardless of practice. I am at my limit in terms of hotkeys, it's just not something I can improve in that dept. So it's click some of them or don't use them at all. FF14 has so many abilities (like old WoW) that there are are simply too many for me to hotkey everything I need so it's main abilities and short cooldowns, whereas longer cooldowns I click. If I get used to the timing on boss abilities I should be able to avoid that problem (I have in Unreal/Ex1&2). It also means I'm coming into this with a major impediment that most people don't have to deal with, that was one of my major reasons for not even trying.

I only have 1 job geared out at 590+ presently, SMN, I thought about MCH, but I can't play BRD or DNC with any kind of skill. Also, with how far MCH is behind every other DPS it felt like a huge handicap, if I could get SMN even close in terms of performance it would easily out-DPS MCH. SMN also leaves the door open to playing rezmage with the same gearset if I need/want to (I'm not as good at it, but I can play it ok). It would take me a couple weeks of grinding to get another job to 590+ and that is the bare minimum I'm willing to enter this in order to stack the deck in my favor as much as I possibly can.

The technical issue of "I'm fighting my controls", rebind them all to whatever you think is comfortable. Same issue people with other games on either KBM/Controller while people got used to it effectively such as MH, Apex Legends, etc.

Shift/CTRL/ALT modifiers, Q, E, R, 1-5/6, etc. Controllers? I have no suggestions, just that people are good on it.

[Issaella]

I've literally tried every possible solution, like I said, I've been playing MMOs for 20y. If I use both shift and control modifiers I will hit the wrong one a non-zero percentage of the time, regardless of how much I've practiced it. If I try to use anything beyond 7 or shift+6 I will hit the wrong key a relatively large percentage of the time. Again, despite endless practice. So about what I have is 1-6, shift+1-6, e/q and shift+e/q (the latter pairs generally I set for cooldowns and movement abilities). Even with shift+5 and shift+6 after half an hour or so it starts making my hand hurt, which is an entirely different issue. I can handle MCH, SMN, DRG, and RPR with only clicking my big cooldowns, but other jobs with more abilities means more clicking. I can almost do RDM, but mis-tapping the melee combo still give me issues, I was really hoping they would compress that into 1 key like they did with the GNB cartridge spender. Tanks and healers aren't as big an issue so I don't have as much issue there, either do to fewer primary abilities (WAR, GNB) or the simplified DPS rotation (WHM/SGE) allowing for more efficient clicking.

[IdowhatIwant]

I've literally tried every possible solution, like I said, I've been playing MMOs for 20y. If I use both shift and control modifiers I will hit the wrong one a non-zero percentage of the time, regardless of how much I've practiced it. If I try to use anything beyond 7 or shift+6 I will hit the wrong key a relatively large percentage of the time. Again, despite endless practice. So about what I have is 1-6, shift+1-6, e/q and shift+e/q (the latter pairs generally I set for cooldowns and movement abilities). Even with shift+5 and shift+6 after half an hour or so it starts making my hand hurt, which is an entirely different issue. I can handle MCH, SMN, DRG, and RPR with only clicking my big cooldowns, but other jobs with more abilities means more clicking. I can almost do RDM, but mis-tapping the melee combo still give me issues, I was really hoping they would compress that into 1 key like they did with the GNB cartridge spender. Tanks and healers aren't as big an issue so I don't have as much issue there, either do to fewer primary abilities (WAR, GNB) or the simplified DPS rotation (WHM/SGE) allowing for more efficient clicking.

Keybinds will make a huge difference. I can't stress enough how important getting keybinds set up in a way that you a comfortable with improves your performance. Best way is to make a system where certain skills are always going to be certain buttons so that all jobs you can use the same system. Once you get that all set up it's just getting muscle memory from that point on.

[LeonKeyh]

I've literally tried every possible solution, like I said, I've been playing MMOs for 20y. If I use both shift and control modifiers I will hit the wrong one a non-zero percentage of the time, regardless of how much I've practiced it. If I try to use anything beyond 7 or shift+6 I will hit the wrong key a relatively large percentage of the time. Again, despite endless practice. So about what I have is 1-6, shift+1-6, e/q and shift+e/q (the latter pairs generally I set for cooldowns and movement abilities). Even with shift+5 and shift+6 after half an hour or so it starts making my hand hurt, which is an entirely different issue. I can handle MCH, SMN, DRG, and RPR with only clicking my big cooldowns, but other jobs with more abilities means more clicking. I can almost do RDM, but mis-tapping the melee combo still give me issues, I was really hoping they would compress that into 1 key like they did with the GNB cartridge spender. Tanks and healers aren't as big an issue so I don't have as much issue there, either do to fewer primary abilities (WAR, GNB) or the simplified DPS rotation (WHM/SGE) allowing for more efficient clicking.

Unironically; Play with a controller.

Pick a job that you haven't leveled that you've been meaning to check out (or start a new character) and level it using a controller. After playing FF14 with a controller, I can't go back to hotbar combat MMOs with keyboard.

[histoireancienne]

I only have 1 job geared out at 590+ presently, SMN, I thought about MCH, but I can't play BRD or DNC with any kind of skill. Also, with how far MCH is behind every other DPS it felt like a huge handicap, if I could get SMN even close in terms of performance it would easily out-DPS MCH. SMN also leaves the door open to playing rezmage with the same gearset if I need/want to (I'm not as good at it, but I can play it ok). It would take me a couple weeks of grinding to get another job to 590+ and that is the bare minimum I'm willing to enter this in order to stack the deck in my favor as much as I possibly can.

If you like MCH, play MCH. As my static told me when I was feeling bad going MCH this tier vs. DNC, "You may be hitting like a wet noodle, but you're OUR wet noodle, and we're not going for a week one clear, so it really doesn't matter." I was also told by multiple experience raiders - when I was wringing my hands about MCH damage before the tier dropped - that it was much more important for me to be on a job I was comfy & experienced with. We had P4S down in ... 5 weeks? Which isn't amazing, but also isn't bad. Damage checks were never really the issue & I certainly wasn't holding the group back by not playing DNC or BRD, and I was also contributing my fair share (we also just needed a physical ranged, period - I don't know about Aether's PF scene, but it does seem on Crystal that physranged is in "high demand," relatively speaking). If you're comfortable with the job, it's NOT a "huge handicap" unless you're in a top group going for a clear week one. (Yes, I do wish MCH got a little more love than a smattering of potency buffs, but here we are)

Have you tried using a controller, vs. kb/m? This game is very well optimized for it, esp. for classes like MCH and current SMN that don't have lots of buttons. I switched from PS4 to PC & still play on controller. The only class I really have "issues" with is AST, but I know plenty of people who raid on AST on controller & do more than fine.

And, as Packetdancer notes, hitting enrage at 25% is a group problem, not a YOU specifically problem. Seeing enrage, period, does mean you've seen the whole fight.