Originally Posted by
Aldracity
I agree that there should be a mechanic to discourage overhealing, but I think threat ends up having the wrong effect.
If the tank is facing mobs the wrong way and AoEs are flying around everywhere, it's clear that the tank is at fault. If a DPS goes full burst rotation on the wrong mob in an AoE pull and gains aggro, it's the DPS's fault and they end up dying. In all these cases, it's abundantly clear that the player at fault is what's causing the issue.
Healers on the other hand? Overhealing a target does not inherently create a problem. Yes, it's a problem on extended bosses when the healer runs out of mana, but in shorter fights there's no clear, direct feedback. That's supposed to be what the extra threat is for, but it ends up sending the wrong message because a loss of aggro is more intuitively attributed to a failure of the tank than a failure of the healer.