The thing about the Sunken Temple of Qarn is that it's the first truly challenging and complex dungeon and those fights can be a REAL pain in the backside if you don't have prior knowledge (specially the stuff that the tank needs to lure into the right places, the bees an the AoE adds of the final boss). People who're running it often might be out of patience.
I dunno if later dungeons are treated as such and, sincerely, my first time doing Qarn was me and a friend (me DD him healer) with a tank that never got past the bees and a really awful DD but everyone was pretty kind. Mayhaps it was just a one-time experience?