Yes and no. You just said what I did. OT has to execute their enmity combo, and that was the problem.
Let's say OT is already in the middle of DPS combo: Can they get their enmity combo + provoke just in time before tank buster ends and MT gets auto attacked?
Should they cancel their DPS combo and start with the first rotation skill?
Please consider the fact that MT is still in tank stance thus still having increased enmity generation, yet necessary to mitigate incoming tank buster.
OR (as an example and what happened in many PUG farm groups) MT is doing their DPS combo, e.g. Zerk triple Fell Cleave and Holmgang'ing in A10S. Try to get aggro from boss then. It was nerve-racking without shirk.
I am not saying you couldn't manage in statics. This problem occurred in PUG nevertheless.
I have the feeling this whole "shirk" incident happened to you.
Nobody said its the right thing to do! It's not. (Heck, I don't even equip shirk when I run a dungeon, better take an additional mitigation skill.)
YET neither is calling someone names. And that is what this BLM did.
Nobody in this story were right.
