Issues enjoying RDM

[Rilifane]

If RDM had the same damage as everyone else, then it would make it the most worth job to take into the group.
Why take BRD, BLM, SAM and MNK when you could go 4x RDM and have entire team immune to wipes?

That's not how it works. Hard enrages and 8-person mechanics are a thing.
While a RDM/ SMN can salvage a try where both healers managed to blow themselves up that would be a wipe without an additional raise, a death is still a death and often results in further deaths, botched mechanics or trouble with the enrage timer unless the boss is securely on farm.
DPS raise is all good during prog as it draws out tries to see more mechanics but you won't beat the boss if the raid is still at a stage where people die left and right from mechanics, no matter how many raise you have.

Edit: plus Limit Break gauge fills MUCH slower and you don't get the full stat bonus, resulting in a dps loss overall. Not to mention the hassle of gearing up several players of the same class.