The suggestion at hand was specifically about getting the player to use their AOE ability, so I was focusing on that part. But yeah, the level difference is quite varied between the jobs, especially in regards to their full AoE combo.
@topic: I can't look into the heads of others and what I've run was almost always without a horror story (if at all I was the root of evil in it XD), but even outside of an efficient playstyle, I find it weird why people would not use their full skills available. I mean, I'm by no means a competent player: I run most MSQ and flying-required dungeons once and haven't unlocked any optional content, unless I get them in roulette (until I "burned-out" of it) or am motivated to do Trusts; i. e. my ability to do mechanics may be like russian roulette. But for me it's common sense, for lack of better words, to use my tools as good as I can, even if I never intend to memorize some opening/burst rotation.