No, I have seen many times when it was quite intentional, and obvious. There was a time, back at the end of WoD, when it was happening so frequently in there, that I quit queing IoC at all.
I am not defending anything. I am stating that it does happen. You can try to chalk it up to “l2p” all you want, but it does happen. Like I replied to Shadows, it was occurring even before merc mode was a thing, so it isn’t necessarily only mercs doing it, sometimes people are just jerks.
This occurring is not about learning to play. Hate to break it to you, but not ever single issue in bgs can be corrected by “l2p”.
Maybe it’s just me, but on my characters that do have a tank option (DK, DH, ect) I don’t even have taunt on my action bars while DPSing. Why? I don’t want to accidentally hit it and cause problems for the person who is actually tanking.