Can someone give me an in-depth explanation why Summoner is arguably the worst DPS?

[Leonus]

This just isn't true at all. You even said it yourself, ranged have to deal with more mechanics so therefore, with similar single target damage, melee DPS would still be ahead due to a higher uptime on the boss. The current melee > ranged gap that exists is just too big, especially since melee aren't even in more danger of dying than ranged in Final Coil. The worst time melee ever got sat in this game wasn't even due to damage, it was due to Garuda's stupid anti-melee mechanics.

You either ignored or omitted part of what I said. Groups found ways of giving mdps higher uptime by having ranged dps handle majority of the mechanics that would require a melee dps to leave the boss to perform them. It's not even the rdps some of of the time, the healers handle quite a bit too and of the rdps usually it's the brd. People found it most effective to have the mdps deal with just the mechanics around the boss or directly targeted on them as much as possible.

If you want to get down to the nitty gritty of it. Melee could handle the same mechanics, but would loose far more dps than their rdps counterparts. In the end mdps always have to get back to the boss. Melee gap closers aren't up enough to compensate for the need to be in melee range. Shoulder tackle is every 30 seconds, drgs SSD (50 seconds?) and DFD (1 1/2 minutes?) and shukuchi for nin at 1 minute. Rdps can be almost anywhere after handling a mechanic and still do damage to a target without having to close as large of a gap, if any technically. (Unless preparing for the next mechanic which everyone does). Melee don't have that luxury unfortunately.

I think people have taken advantage of melees higher damage output and ranges mobility to keep optimum damage on the boss for the raid. The same could not be said If the roles were reversed. The scale, I feel, would heavily swing in rdps favor if/when rdps can equal or be close to mdps output (which blm currently can do with enough procs). You gain more than you loose by cutting out mdps in party makeups at that point. You get the dps and mobility in which both mdps/rdps lack in one or the other.

though I would say, if rdps got to be on par with mdps in dps, mdps Should get a big reduction on their timers for gap closing.

Anyways, idk how much more ST dps smn should have over blm. Too much and blm will complain until they get a buff because the feel irrelevant in content. It seems hard to balance on without starting a back and forth buff my class war. I like the idea of better Mp management for smn. Idk why, but I always found blm infinite Mp a tad bit ridiculous.

[Dwill]

Snip

I think you're the one who didn't get it. I'm not saying melee should handle mechanics. I'm saying that if melee gets more uptime on the boss due to ranged doing mechanics, ranged should have a better chance at competing against them in damage output because of that lower uptime.