I don’t see a real solution to it.
Letting healer/tank/dps happen against
another healer/tank/dps or healer/dps/dps has some really bad outcomes for certain classes.
Like healer/tank/dps vs healer/tank/dps where one dps is a Fury Warrior and the other one is a Ret Paladin. Ret Paladin is strong and all, but the lack of MS makes it extremelt unlikely that the ret can kill anything as a solo dps against tank/healer. The ret probably goes 0-6 in this matchup and it has nothing to do with skill.