Without positionals, you'd need to buff all melee DPS jobs. Monk in particular as everything on him has positionals and some special effects such as guaranteed crit on the back during bootshine. Also I feel like it'd make it just as boring as playing a tank minus the aspect of mitigating your damage properly which would make them the overall most bland jobs in the game. They would need more than buffs but they'd need another quirk to compensate and to make for more engaging gameplay.