Who said we are? my group uses it for the 1st set of 5 while the rest dps him. after that we have the tank get a few (of the 5 group) and the rest get them.
The issue pvp rating has, and that M+ rating would also have, is that it brings everyone’s MMR down or up based on the team’s lose/win when it really should look at how the individual player is contributing. If one player is playing like 2200 and the other like 1800 then the 2200 should get an MMR closer to 2200 and the 1800 should get an MMR closer to 1800 whether they win or lose their 2000 match.
In an M+ run, your MMR would be right when you get into groups where you’re making 20% of the group’s mistakes. But just like pvp, the group will carry someone who makes 65% of the mistakes to a win, and they would move up to a better group where they will make 70% of the mistakes. Then above average players would get stuck with a lot of carried players at the same MMR because they carried those players to time the same keys as them. Raider IO has the same problem which is why keys feel so frustrating late into the patch, everyone has been carried a bit by better players and the score reflects how well they can do with the best players they’ve ever played with. Which is usually more than how well they can do with four players who have equal skill to them.
A solo queue M+, with WCL analysis level individual MMR design could be really useful and interesting. I’d try it.