If I died and just got rezed, using Shirk is not really doing anything, I'm starting at zero enmity. If I died and want to get back into the OT duties, I need to Provoke first and then Shirk. Yes, I should not be dying to begin with, but sometimes things happen, some healer may mess up, or be busy healing people. Hell I may @#$ up and forget to use my click action before a fiery Lakshmi off tank focused mechanic. Point being: that is when I want that combo the most.

I *could* just provoke and use a low enmity combo, too, I will likely lose agro next MT attack, but that runs still the risk of me keeping agro if the MT is feeling comfortable and no longer using agro combo and maybe even in DPS stance.