As an absolute BASELINE, tanks NEED to do MORE damage than healers. Healers are the quintessential make or break role... you suck at it, everyone dies, you don't do enough damage? It's noticeable.

There's a huge difference between an optimized healer and a non optimized one. Their damage shoots through the roof as they peel back all of the bandaid panic heals and replace those GCDs with damage gcds.

Healers have a clear pathway for damage progression: less healing, more damaging.

Tanks have no such thing, really. The combos and rotations are braindead easy, and honestly, almost all of these fights can be solo tanked without the introduction of a "forced gimmick" that is forced for no other reason than to force two tanks to be brought. Seriously. Looking at the busters in this tier, how many of them are designed not thru damage, but thru sheer gimmicks to require two tanks?

If I do 9k or 11k dmg it doesn't matter. I don't have a big impact. The skill floor is so low for tanks, the skill ceiling is so low, for tanks. But there's a HUGE difference between an 11k Greyville monk and a 18 to 19k OJ monk. A good dps player is noticeable.