The rage button has changed from the taunt key to call for medic key, so there are no problems as to when bosses rage and taunt at the same time. In addition, some bosses such as Seeman and Volibear (taunt_laugh) have custom taunts. I seriously doubt there being issues with friendlies as voteslay, hammers and timers are present. I also hear a lot of new players questioning the incapability of bosses taunting.

Meh if you taunt during the time you are supposed to kill the merchs, you are only wasting time. And after you have killed them all there is very little time left, so imo its a good tool to keep hales from timewasting.

Seen too many friendly taunting hales in my lifetime....

Really? I don't believe that's true, considering the anti-timewasting tools and the amount of tryhards on the server. Taunting after killing that phlog pyro who was pestering you or quickscoping that fully charged medic is pretty satisfying.