The obsession with "efficiency"

[Firepower]

I think every job is been excluded at some point, aside from DRK and NIN from what I can recall.

You missed out:

ALL tanks excluded from Ramuh EX because SMN's Titan pet had overpowered aoe magic resist completely bypassing the tank swap and surge protection mechanic of the trial.
Brayflox Hard: BLM being the only DPS allowed on runs for animus tome grind.