MCH aoe is prob due to the aoe's outside of bioblaster not being that great, shotgun is very meh on more than one target, nobody is gonna stand in the turret for more than one tick and any decent opponent isn't gonna wildfire their own team if they can prevent it, so all you have left is short range bioblaster, and a line aoe chainsaw that is very meh without target being <50% and analyzing it.

White mage not being S and even being below sage is strange though, strongest non lb cc, one of the strongest lb's, great healing, great burst both aoe and single target, one of the top jobs in pvp right now for sure.