Balance the matchmaking, Don't demote if u are doing good

There is no way to determine how good you are playing based on numbers alone. Just because you have a high KDA and a lot of gold doesn't mean anything if you don't use it correctly and work with the team. If you were doing so well, you should be helping your lanes that are hurting and get them fed. Perhaps give kills away and help teams force objectives.

Honestly, as a Garen, it should be easy to do that, but I bet you just used your Ult to secure kills for yourself and played greedy the whole game given that you only have 3 assists.

And how about support mains? How would you make it balanced for them? They should have high gold or kills to begin with, so they should just be demoted?

Come on, you don't get demoted because you lost 1 game, you get demoted because you lost several and your MMR went down. If you can't carry from being ahead, then it's pointless to reward you for being ahead.