That’s not true. Not all builds have 30 or 40k life and even res and armor capped, those builds can get one-shot by most of the ladder boss attacks. Either they are fast enough to take down the boss before any attack or they have to avoid the attacks. It is option 2 when the Bosses have immunity phases.
Evading, avoiding attacks seems pretty standard stuff in a video game. I know, sometimes D4 makes you believe that you don’t need all that. Maybe that’s the real problem here.