Putting aside the likely impossibility of them overhauling the entire gameplay system to support another role. A pure support role in general just wouldn't work in this game.

Balancing it would be damn near impossible because you either have enough support to supplant a dedicated DPS, in which case you always want that job/role. Or the support isn't enough to supersede raw damage, in which case nobody would even think of bringing one. At best, they'd have to force its inclusion via the 5%. That doesn't exactly make for a worthwhile investment.