Again though, this is not a revenge mechanic. VIIR's combat system already doesn't let you endlessly wail on an enemy the way you can in KH to begin with.
I mean. It sorta is. It's a mechanic that prevents bosses from being stagger-locked and steamrolled. It keeps the boss battles flowing at a specific pace to prevent players from just overwhelming and bypassing the boss's struggle.
It's literally just getting interrupted by having cutscenes and such to punctuate phase transitions. You get punished for not knowing in advance when a phase transition occurs, nothing else. If I use a limit break and the boss is 1HP away from triggering a phase transition that I wasn't aware of, my LB will do a whopping 1HP damage.
Don't use limit breaks early in the fight. That's a simple strategic decision to make to avoid DPS waste. Phase shifts happen 90% of the time when a boss's HP is near the half way mark. Sometimes it's the 25% and then 50% mark. An observation to keep in mind as well.
Yes, the boss fight interruption is to prevent high leveled and sophisticated players who've figured out weaknesses and exploits in the boss, from getting to easily defeat the boss with no pushback.
I honestly don't get how players think this is somehow "unfair."
You are winning when this happens. The tide is in your favor.
The only fight I can imagine this being truly problematic for, is Hell House. Because Hell House is coupled with long ass cutscenes and it
Just makes the already long boss fight even longer.
You keep approaching this from the angle of a player just completely in control of the game from top to bottom and this phase change is the only thing preventing the game from being 5 hours long. What is much more common, especially on a first playthrough, is that you fought tooth and nail for that stagger, and long enough that getting it took you almost all the way to the end of this unmarked phase, all while barely keeping your party up and in fighting shape. Maybe the fight already had a phase change so you have even less reason to expect another. You finally manage to get that stagger bar filled, and unleash the limit breaks you've been clinging to through the fight, only to have them be completely and utterly blocked, without any way to know you were up against a phase change, and their stagger bar resets to zero, AND you lose the whole limit bar. That's shitty.
Then don't use your Limit or Summon early in the fight!
I don't understand how this is so unfair. Like, that's the most rational and obvious strategic decision to make once you learn of the mechanic's function. Save your load for the final push of the fight.
And if you're in that desperate of a first playthrough situation where you're barely hanging on and pushing the boss into it's first stagger, then it's highly unlikely your DPS is to the point you
overflow the damage into the next phase. How are you simultaneously on the edge of defeat but also able to blow out a boss's early HP guage?
You have to seriously damage a boss by a hard percentage to get that marker to appear. And that's extremely rare in a first newbie player playthrough. If it happens, they're highly leveled or skilled.
Having your spell cast be interrupted can be annoying, but it's just one spell cast. Not nearly as momentous as a limit break or Summon finale. And at least he spell is being interrupted by an enemy actually attacking, and not just some invisible wall.
I'd argue that's worst given hard mode and the scarcity of MP. That can be the difference between an Arise or a Life.