Most tanks don't use CDs in DPS stance to mitigate autos better. They see a vid or learn DPS stance is what you do, but not whats behind it. Their CDs just sit while they pew pew pew. Healers either get behind and the tank dies or wastes CDs healing instead of DPSing. Most of the base tries to emulate top groups, but don't play like top jobs.

Honestly, I'd like to see someone crunch the numbers. Which is better net party DPS effect? 20% increase of Tank in DPS stance with a healer blowing CDs to heal him. Or a tank in tank stance allowing the healers to DPS more. I say, healers, because it affects both healers

My hypothesis is the net party dps would go up in raid if tanks stayed in tank stance allowing both healers to DPS more.