I’m not sure what you’re babbling about, but the point isn’t that a great player can’t climb, it’s that the MM puts trashy players in all your matches and unless you can carry them, every game, you won’t climb.
You actually believe people get banned for boosting. Now that’s funny AF. Mercy is one of the most boosted players in the game, and if you think they are banning those players you’re a special kind of stupid.