Originally Posted by
Disc
DRK/PLD compete for the MT slot, not OT. MCH/BRD compete for the ranged support slot, not melee/caster. BLM/SMN compete for the caster spot, not melee or ranged support. Doubling up on casters or ranged support reduces the effectiveness of the overall party composition due to either loss of maximum damage or loss of support abilities, but like PLD/DRK, is still workable in most situations.
I honestly prefer it like this. Leaves room for a new fourth tank to compete with WAR for OT slot & allows all tanks to specialize more in a specific role.