I don't see the argument for people who say +2/-2 MM was unfair and hard for tiers 5-6. My Wolverine/Hellcat had a nice time grinding. KV-1 to KV-1S was pretty smooth, much easier than ANY other Tier 5+ grind.
The argument that people pull out saying: Unicums/people just want +2/-2 MM to seal club in Tier X, please do shut thy petty mouth up. That's not true, and that will never be true. So don't give out a false argument that you want to believe true.
Overall +2/-2 was better. I was able to contribute more TO THE ROLE OF MY TANK as the lowest, middle, and highest tier of the game. I can feel the majority of people during +2/-2 were playing their role: TD support, Heavy brawl/push, Medium flank, 'light like' tanks scout and flank. Carrying the game as a lower tier felt more accomplishing, and was actually the best matchmaking, "sacrificing" (for those who complain the harships of tiers 5-6 grinding) tiers 5-6 stock grinds for a BALANCED Tiers 7-10 games that had VARIETY.
However, needless to say, Wargaming will never implement this as low skilled players will complain, new players will leave, and general decrease in PROFITS; and overall player skill goes down, why use strategy when you can just point, shoot, switch to APCR/HEAT and win?