Let’s be real, the tank / healer / assassin / 2 flex thing doesn’t really solve any issues with QM matchmaking. It may make some games slightly better for heroes that rely on a frontline to do well such as Jaina or Kel’thuzad, but it’s really not going to solve the real issue with the matchmaker.
Skill level is all over the place. There are huge, noticeable spreads in player skill and it’s quite annoying.
If you actually want to fix the problem, tighten the allowable MMR ranges. Comps only superficially make you feel better about the match.
Ok, so it makes the match slightly more enjoyable for Greymane, Malthael, Jaina, and a few others.
By that token, it also makes it worse for heroes like Illidan, Valeera, Butcher, Nova, et cetera.
Let’s say you get your tank, and your tank just spends the entire match thinking they can 1v5 the enemy team like what happened in my last match. Has that solved the issue? No, that low skill player just threw the match hard.
Relatively equal skill is FAR more important than comps. Enforcing comps without consideration of strengths and weaknesses only superficially makes you feel better about the match.
It does though.
Tighter MMR spread is a non brainer but enforced comp showed that it is not an easy task to achieve especially when enforcing comps.
Tragedy is that you may end up having as long waiting times with the same crap comps when ticking your box aka worst from both ends.
Or course telling you to go to URD to mitigate both is a waste of time.