"You pull, you tank" is a bad mentality

[Deceptus]

I've seen healers keep DPS alive through tank busters and double pulls. If they can do that, they can keep a green tank alive.

As a healer who has healed DPS through the above, this is 100% correct.

Trash pulls don't really need a tank if the DPS is decent, a healer can keep them alive. Hell, depending on the boss, a melee can tank just fine.