Enmity build up on untargetable bosses

[Lyrica_Ashtine]

Snip

I believe I've mentioned several times how it wasn't a problem with the old content with how White Mages work and how it isn't a problem now with how the content is. Please read more carefully. I've brought this to attention as it may present a much bigger issue for future content and/or future jobs. Even if it's not a serious problem now, it's more of a pain in the ass gimmick more than anything for everyone:
Healers take more damage than tanks, losing GCDs left and right till the tank re-establishes hate. Which can be one hit or several hits depending on the situation
Tanks lose output potential as they're forced to perform enmity combos over damage combos which they normally could without that transition
DPS lose positionals because the boss is spinning left and right

First of all, I do not consider paying normal costs for performing role actions a disadvantage. Healers are not in any way an exception as they continue to perform their role - healing - despite the boss being removed. That ASTs can perform similarly to a WHM but have a a greater difficulty to manage enmity is a problem inherent to AST design, not encounter design.

If not the healers being at a disadvantage, then tanks are at a disadvantage. If you consider "performing role actions" as "normal", then tanks performing enmity actions on the boss would be normal too. But they are unable to do so as the boss cannot be targeted or is invulnerable.

The quote you highlighted has nothing to do with the DPS focus the game has at the moment, or healer DPS.

I brought it up as it's something healers would do aside from just spamming that single button to keep the tank's HP bar up. Enmity buffer would only last for so many actions and someone else in the topic shared his/her experience in thordan EX. Said person also mentioned he/she was DPSing. That's one way to artificially lower your enmity for a phase. But why would good healers who can do both mending as well as maiming be punished for pushing their limits?

It's not much of a choice for a certain tank job either. Paladins pretty much have to repeat their Rage of Halone combo to build up enough enmity to last through the Ultimate End phase.

No it would not. That would be just terrible. I have never stated that "Sephiroth Dives" are desired.

But currently (as far as I can remember at least) only one encounter has this element. Just as it is possible that a future encounter may include such an element again, it is equally if not more likely that such an element won't be present considering what we've come across in the game so far. I personally can't advocate change based on such conjecture. The picture you paint regarding healers getting destroyed the moment a boss returns to fight is in my opinion misleading.

Although not as extreme as T9: https://youtu.be/4v4nmg-fsIs?t=14m15s

While there was time to Provoke, any form of action being taken before the next tank action has effect will outhate the effect of Provoke.
Then there's the thing that Square-Enix will have to consciously design content that doesn't open up with a hard hitting move. I believe there would be more coordination in preparing for the next phase by positioning properly. Rather than take a beating and try to recover.

I'll just repeat it once more, as you seem to keep ignoring this:
It wasn't a problem back then due to how Shroud works and still isn't a problem for White Mages
It isn't a serious problem now as current content doesn't open up a phase with heavy damage moves
It may be a problem later unless content is specifically designed to:
...have nothing that will utterly destroy someone upon phase change
...have short invulnerable/untargetable phases
...have sufficient amount of time to build enmity for the phase where they cannot for the duration of it
...make any tank/healer combination work (even if sub-optimal) if the duration of such phase is long

This issue doesn't only concern healers (except for White Mages, I guess) and there's no valid reason why this is a thing. If "management" and "ability" was really a thing, consider it from a tank perspective:
Certain adds spawn with initial enmity build on adds:
Oppressor and Oppressor 0.5
Living Limb appears with enmity build up on Living Liquid
Ser Janlenoux and Ser Adelphel appear with enmity already build up on King Thordan
Everyone builds up enmity on The Manipulator while attacking it's legs (or healing for healers)

If you consider A4(S), why can't this be a thing for other encounters?