Whilst I think the mmr system is fine I do agree with your general statement.
Tons of bought accounts in my games lately. Some smurfs some cheaters some throwers/derankers/boosters.
There are patterns to the bought account names and I've never gotten a successful report/ban message from reporting any of them.
Calling out a cheater or booster/thrower either results in them going silent or just turning it up and stomping the game. Still no ban message after.
Multiple high rated radiant players have wintraded/boosted or cheated their way up the ladder(wouldn't surprise me if they queued/queued at the same time as cheaters) All you have to do is check their games and see who they are winning with/losing to in roughly 10-30% of their games at any given point.
