Square enix get rid of FATES.

[Kyana]

Lower FATE EXP (a bit) and especially company seal reward (a lot) and give NO EXP for individual FATE mobs killed.
At the same time, boost party EXP and chain bonus for normal mobs.

That's what I would try.

It's just sad if you join a lvl50 dungeon and your tank obviously has no clue what he's supposed to do because there was little need to tank while leveling.
I blame FATEs for the, sometimes incredibly bad, performance of players in a normal party situation, because all they experience during the leveling process is running from one spot to the next as fast as possible and try to hit as many mobs as they can.