This is my pet peeve as a healer. Nothing worse than the Black Mage who thinks that their best way to do DPS is by standing as far away as possible from the group. The worst case this happened to me was in Void Ark where I had 3 black mages in the party and for every single boss battle they would immediately spread out to stand as far away as they could from both each other and the rest of the group. I couldn't even find a spot where I could single target all 3 at once never mind also being in range of the tank or including them in aoe heals. Beyond frustrating. I get that keeping a distance makes it easier to avoid certain types of AoEs, but there's a point where it becomes extreme to the point of bringing down your group. Summoners, Machinists, and Bards don't seem to have this problem staying reasonably close for some reason. Thankfully with the nature of Red Mage melee/ranged hybrid combat I don't think they will either.
