which is why is said "a mix of damage and survivability"
no matter how you look at it, it still boils down to these two things:
-can you deal enough damage to the boss?
-can you survive attacks from the boss?
in my case, it could be a grid issue, but not in the form of damage (again, 50k-70k damage PER HIT... that's quite a lot per round). it'd be in the form of HP.
every single team thrives on this to some point... it might be 50% damage and 50% suvivability for some cases, it could be 99% damage and 1% suvivability in others... but can never forgo survivability entirely for the harder content unless you're packing something quite strong like 120%-130% assault and double 100% eidolon or something... (even then, most players have access to 40%-60% eidolons anyway)
and keep in mind that while some players have made it to points where they can solo even the catastrophes, not everyone has gotten there the same way. in the process of building your way to that point, your tools might be different. in my case, i don't have amaterasu (she'd be a big help) or summer sol, so it's either bryhildr on her own, or with help from sakuya for the most part for my fire team, and that's if i can even debuff (wind ult gives huge middle finger to debuffers). it may not be a case of healing for them, but for 7-8k HP to get shredded through is kinda ridiculous.. especially since that tends to be the range people stop getting defenders if they even have them
my point is, this game is about strategy. maybe the kill it before it kills you thing can work at times, but for some cases, it doesn't