The most common situation while doing massive AoE is to pull aggro on loose add's, just because the tank has the duty to keep aggro. Even before the tank reaches the pack of mobs there goes the
Le AoE rétárde will often post his recount meters at the end of the run, showing how much skill he has to click a shortcut and place it on the ground. Some classes don't even need to place the area of effect, cause that would complicate the class too much.
Piece of advice: Do not try to talk about how bad the person is playing, always doing aggro just because he doesn't know to play. That person will eventually tell you suck, because u can't keep up with is damage, and ur just jealous cause u can't output 2000dps at lvl40.