Yeah I’m going to go back and point at fight design again for this one. Look at any of the dungeon leveling bosses, alliance raids and even some extreme trials that I can think of. The telegraphed attacks often don’t kill you if you fail they just give vulnerability. The aoe pulses will never kill you out right but they will one shot you after a few vuln stacks. The aoe pulse isn’t a heal check for the healer, its a mechanics check for each player.
“You can’t heal dead, but you can shield stupid.”
No amount of healing prevents 100->0 shots on a character but shields/mit can increase the number of stacks you can take before you get one-shot. No amount of healer changes will change that until healing is mechanically nessasary for more than just reseting before the next mechanics check. Heal absorbs/“white hole” effects are a step in that direction but again thats a fight level change.