It depends one the tanks what they wanna do. If you have a tank that just ‘Tanks’ in tank stance then voke + shirk is not needed because he will never lose Aggro (except death). If you rather want to do dmg like many tanks want to you drop tank stance and if you have good dps you will sooner or later lose Aggro when you don’t spam Aggro combos. Voke + shirk gives you the lead you need so good dps never catch up with you even if you go dmg stance.