None of those reasons come across as particularly impactful, and this is assuming you are even correct. Point 1 is a bit ridiculous and not true. The main point in WoWs history that is famous for ninja looters was vanilla, where xmog didn't exist sooo... Points 2 and 3 I can see I guess (but it's still a non-issue) and point 3 is just weird. You know how a fight is going to go because of your buddies gear? What?
If you are saying that you could assume how good/bad the player is based on their gear and adjust your gameplay accordingly, then that's just silly af since all you have to do is inspect them to see their gear (which you should be doing ANYWAY to check enchants, etc)