I was kinda expecting the answers you got OP, but I agree with you, many parties will leave if the tank doesn't know something or a dungeon, but God forbid we treat the DPS or healer the same.

Last night I was in AK with the usual pug, no one talked or said anything, I always ask this before a boss "We all know this fight, right?" I'm assuming this since everybody is quiet, so I get no answer and assume it is so and pull, then I see our DPS neglecting adds, then everybody, including the healer stand in the red ring from the big golem, of course we wiped.

... I explained the whole fight on the second try and we got it, DPS and some healers are just spoiled and seem to think they should be carried by tanks.