I’m sorry, but as someone who tanks on Warrior (but also frequently heals) this brings a grin to my face. Normal difficulty content can be handled even when one party member is incompetent or dead, so long as everyone else knows what they’re doing. It has to be, or else casual players wouldn’t be able to reliably clear it. I never tell my healers this when I’m tanking because I don’t want to hurt their feelings, but I am endeavoring to use my job abilities as best I can to make their presence redundant.

But to take this in the other direction, as I mentioned I also heal pretty frequently (on Sage) and I have been in dungeon parties where the tank has disconnected. If they take too long to come back, I absolutely will heal the DPS through mob packs and some boss fights without a tank. Should the tank feel useless because we could clear the dungeon without them? No, that’s just the way dungeons are designed: with enough slack that any player can be missing or incompetent and the party can still clear. If everyone is good at their jobs, that just gives you a safety margin.