Skill level necessary to clear HW MSQ content

[ItMe]

Sounds like it's not so much skill you need, just time to learn mechanics. That's not strictly something that "carries over" into MSQ or anything.

[...]

Again, would say that there's little skill to gain from harder fights. It's less about skill, more about mechanics. If you're unprepared for a mechanic and get hit, you'll start to learn how to handle that mechanic. But it's not strictly something that translates to being better in anything else. It's the same game of "dodge the telegraph." You can learn how to do that in Sastasha as easily as you can in Coils.

That's fair... To a point.
But a lot of this game is building on player knowledge as later fights reuse a lot of mechanics, they just have players connect the dots differently.
Practicing up on the early stuff def helps one get an understanding and a feel for how this game plays, and learning how you need to learn mechanics.
Though you may never see Ifrit's nails or Garuda's feathers again, there's still value in learning those fights.

[Hasrat]

That's fair... To a point.
But a lot of this game is building on player knowledge as later fights reuse a lot of mechanics, they just have players connect the dots differently.
Practicing up on the early stuff def helps one get an understanding and a feel for how this game plays, and learning how you need to learn mechanics.
Though you may never see Ifrit's nails or Garuda's feathers again, there's still value in learning those fights.

There is. But I would hold that much of it still boils down to "dodge the telegraph." To that end, much of the skill/knowledge that might carry over is simply learning new telegraphs. Which is kinda just as much just learning fight mechanics. Learning the "no indicator cleave" or the divebomb or the knockback, etc. They're reused mechanics, with different animations each time, so, it's maybe a bit of a 50/50 of recognizing it vs learning what it looks like in each fight. And yeah, nails/feathers falls into this as well, under "kill the adds." Any new enemy that shows up during a boss fight (usually) needs killed asap. Except when it doesn't. Which, those few scattered exceptions throws a bit of a wrench in the learning/skills attempt.

"Kill the adds, don't die." Gets you through the vast majority. Might sound a bit dumb, but, adds are often the real killers in most fights, and need to go down. After that, even if you're not contributing much, just running around trying to stay alive can often be enough to win out by attrition.

But also, I don't main heals, so, much of my advice may fail to apply.

Also, for context, we are here debating the necessity of running ARR EX/Coils, synced no less, to learn these skills. Setting aside MSQ to run that content synced for the sake of learning EX/Savage-level skills to apply to MSQ-level content. To me, there's no real argument to be made there, it's unnecessary.
By all means, if it's a goal, go for it, because it's fun and there's some accomplishment to feel clearing content that most will have never run. But by no means should it be the bar to clear to progress MSQ.

[Iscah]

That's fair... To a point.
But a lot of this game is building on player knowledge as later fights reuse a lot of mechanics, they just have players connect the dots differently.
Practicing up on the early stuff def helps one get an understanding and a feel for how this game plays, and learning how you need to learn mechanics.
Though you may never see Ifrit's nails or Garuda's feathers again, there's still value in learning those fights.

Yes the mechanics get repeated, and you're still going to see it for the first time "somewhere".

But saying that you have to to the extra-hard content first so you'll recognise what to do when you see the same mechanic in a normal-difficulty fight later is putting things back-to-front. If you just continue with the other content and encounter the mechanics there, then you get to apply that to the hard content if you ever come back to challenge yourself on it.

You're either going to need to put a lot of effort into learning those EX fights, or put the same effort into learning the simpler normal-difficulty fights that will allow you to progress further into the game.