Warriors can't heal current endgame content this is a spurious argument. Expert dungeons are not endgame content they are a joke.

You can't use Nascent and Bloodwheting at the same time. Shake it off is not useful on a single target without burning multiple other cool downs, it specifically is a raid utility spell.

Warrior is good at keeping itself alive, this is a tanks damn job, but can only keep a second target alive if they and that second target play perfectly.
Everything they can heal with has a minimum 30 second cd so without already knowing the fights front to back and both they and the other player not making any mistakes they die.

Doing DPS IS in fact as much your job as healing is theirs. Every job has a secondary role of some kind due to solo content being a thing.