Black mages, A7 and its mechanics.
This was actually an idea given to me by a GM after reporting someone for excessive trash talking/attacking another mage for their low dps numbers on a floor 7 DF run and its something alot of people don't seem to be aware of presently:
Alex floor 7 is black mage hell. Most (if not every) mechanic in that final boss fight is geared towards keeping them from being able to maintain their enochain buff/rotation and hampers their dps numbers immensely as a result. From the boss flying off and going untargetable, to the add spawn times during his grab phase...to the giant rolling balls of death and how big that room is without the spikes active, each of those facets come together to make mage life difficult when trying to maintain optimal dps.
The amount of trash talking about mage dps on that floor is somewhat distressing, having parse numbers rubbed in our faces is both rude and doesn't reflect the class properly giving how the mechanics of the fight work against them.