Make friendly fire, not combat tag you.
The reason is simple, Everyone's game or internet connection sometimes crashes. When that happens there is a window of time approximately a minute or so when they go AFK. Allies usually hit AFK people to get their attention. Now you have to walk half the continent again cause your game crashed and you got friendly-fired to death cause of combat tag. I do not know how often this happens, but my first siege since the change and I died that way, so seems like a pretty obvious problem to me.