"Get the job done".

WHM can kill things with nukes, it just takes longer than BLM.

Paladin can kill things with melee, it just takes longer than WAR.

What the hell can't get the job done in the majority of content in this game. Can a Paladin heal and have people survive? Possibly. Doesn't mean anyone does it. Can a White Mage nuke and kill things? Sure. Doesn't mean anyone does it.

Whm nuking isn't popular because it sucks, but it can "Get the job done" fine if someone's dense enough to do it. That doesn't make it less suck.