No hidden MMR is good.
The main reason people complain about the change (besides teammates) seems to be the fact that they had a much easier time in previous seasons. This is evident as pretty much every game, a half decent player gets hackusated in gold-diamond lobbies. Even in crim lobbies more often than they used to lol. I'm crim 3 and have legitimately come across significantly less blatant-enough cheaters for me to notice than in previous seasons. While they obviously need to do more to prevent cheating, not every plat lobby you queue into has a cheater in it lol.
It was probably a bad call to roll this update out mid-season after a season where everyone and their childhood Dobermnann could reach any rank they wanted as long as they played enough. Egos being at an all time high makes swallowing the bitter pill of "maybe i don't belong in the rank i thought i did" difficult, so people default to thinking everyone's hacking as they've never come across players as good as they're up against now.
It would've been better to roll this change out alongside a rank reset. I imagine getting belt long enough to drop all the way from, say, diamond to gold would make any sane person stop playing the game.
They do need to do a better job at balancing teams, but i'd wager having teammates go double negative every game is gonna stabilize as people get to where they truly belong (which wouldn't be a problem had this change rolled out during a reset). I hope the devs don't revert the changes made before we have more data on how it's all gonna shake out. Ranked is supposed to be sweaty and a true test of skill, which i think the current system has the potential of being.
Maybe add a casual CDL 8s playlist with MMR for people who just wanna play 4v4 COD with CDL rules, idk how this doesn't exist yet lol.