Those people annoy me. My definition of a carry, and probably others’ as well, is “If everyone in the group performed at that specific player’s level of skill, would they still succeed?” If yes, then the run was not a carry.
But when you have a group of a tank, healer in a damage spec, as well as two other burst DPS classes, all wearing heroic or above raid gear, don’t get upset at the affliction warlock who just hit the ilvl required to queue for doing almost no damage.