PVE isn't about competition, just because it's you and only you, who determine goals for yourself. If you want to be in quest blues - it's your choice. But... There are players, who have so called "killer" archetype - they're players, who's goal is to dominate over others. They are usually PVPers, but the fact, that Wow is mostly PVE game, brought them into PVE too. So, they find different ways to "dominate" in PVE. I guess, Recount - is their best friend.
Blizzard have to deal with them, only because they're second most widespread players' archetype.
I'm "reward driven achiever" - true PVE player by definition. I hate competition. I tried to play PVP games - it's too toxic for me. Everybody thinks only about stomping you into dirt. If game is unbalanced, biased toward some Meta or matchmaker works too poorly, which causes constant stomps: "L2P", "adapt & improve", "you're common denominator" - are the only things, you'll see on forums. The problem is in fact, that there is no bad players in matchmaker-based game. Essential reason for matchmaker's existence - is to provide allies and enemies, that suit your level of skill, and provide gameplay, that is enjoyful for you. If you're at your skill cap and game is too hard for you - then matchmaker doesn't serve it's purpose. But nobody cares. You're easy frag? Even better for them.