How about "Wipe counter" on bosses only instead of the proposed Death counter?

You could have let’s say 10 bosses wipe per run (vary by the amount of bosses in a dungeon) and if you exhaust them it does the same as if a key timer expire.
No timer/death count for trash so we don’t have to wait for lust/CD for every pull and since only full wipe count (boss resets) there will be less grieving if one or 2 people dies but you still manage to down the boss!
You could also limit the amount of Lust/Hero you can use per M+ run (2 per run?) so you have to chose on which boss to use them.

I think if you’re lust/cd every trash pull you’re already at your key limit and hitting your deathcap wont inhibit your ability complete that key, just your rating acquisition. And if you’re struggling on single trash packs that you need stacked cds on nearly every single one then you should risk depletion if you die, just the same as a boss.

They could add something like where your first death counts as 3 and raise the limit by 10. Essentially making it so players who escape death can make up for other members of their group. That would alleviate some of the toxicity in having one or two poor performers in pugs with a zero effect the moment the group wipes entirely.

Are you seriously suggesting that anything less than 50 deaths should be considered a success?? Like 5 with a 0 after it? I really, really hope I’m getting trolled…

Trash is the difficult part of M+. Anyone who thinks the bosses are the challenge is really not ready to be leaving M0. They are probably a liability on the bosses, which at least in keys around +10, should be no issue at all, and they are almost certainly a liability on trash.

General PSA: For any player who thinks your only job on trash is to zug zug big numbers, you are the reason people leave keys. You are the reason invites are so exclusive. You are the reason keys fail. Every spec has a tool kit. Please start learning to use it, because everyone else is tired of being expected to carry.