I feel like a lot of the complaints that 'this is way too hard suddenly' stem from players who are playing with trusts, and hoping to watch what they do to see where is safe to stand. Obviously, the issue with this is that they're super slow to get there, make it by the skin of their teeth, and in some cases, 'should have been hit' but dodge the attack because they've got trust privilege. So, rather than watch the trusts dodge right on the 99 dungeon elevator boss, get hit, wonder 'why didn't the trusts move sooner', instead it's on the player to look at the boss, the castbar, and try to discern 'why did the trusts go to the right?' (eg on that boss it's because it raised the fist on your left, so the left is not safe)

I worry that some players can't (or don't want to) associate boss' movements and their 'tells' with how the mechanics work, and would rather be told 'stand here' in a game of monkey see monkey do

Also, to be 'that guy', I don't recall us having complaints about dungeons having 'insane difficulty' when SCH had 3 DOTs and AST had the SB card system. It's almost like, if you take complexity out of the job's kits and move it to encounter design, this is the end result: encounters that are super unforgiving, full of oneshots (and if you die in a trust run, it's an instant reset even if you're not the healer), and exclude casuals because 'too hard'. Meanwhile, if a casual didn't juggle Bio/Bio2/Miasma's timers correctly in HW/SB, you'd... clear the dungeon 3 minutes slower. I know which design I'd rather have