I truly get annoyed at this as well. As a BLM I make it a point to focus those adds ESPECIALLY if the other DPS is melee. That is kinda the point of my job after all. I am ranged and can burst things down very quickly, so why should the melee DPS have to waste time running around like a chicken with it's head cut off? My friend went through a similar situation with a SMN in fractal too. The SMN wouldn't AOE and then asked what DOT's were? XD When the party tried to help they said "I don't care about that stuff" and then ALSO didn't even attack the adds at the end boss to top it off. XD