So, PS4 player here without a friend who feeds me information on my parsing. When I'm playing poorly, I know it. You do not need a parser to tell you that. You just know it.

So, yes, the game doesn't do a good job of pointing out that your DPS is mediocre, but players know when they are playing poorly, and still don't improve. All the Proving Grounds experiment did in WoW is highlight the larger subset of players who a) know they're playing poorly and b) do not have any desire to improve. You can communicate in the clearest possible terms that the player needs to do better, but these subsets will not improve because they do not want to.

Yes, the reality is sad and sobering, but it is what it is; and S-E, rightly so, doesn't want to force these players to quit, and any difficulty increase in non-end game content will do that. Other developers have admitted that, from their data, they find that when players hit an obstacle they can't overcome, they often play something else instead of trying to improve.

:| That's the western gaming audience for you.