Matchmaking tries to actively demote people.
Why don't we get an actual statistical match made ladder. If your MMR is low, the game thinks that you should be the one to carry the game. Unable to carry the game, well that is too bad, you are getting demoted.
For someone that has been moving between tiers a lot I've noticed a pattern. Every time I get promoted to plat I'm suddenly in a really bad position where I can't get anything going for me.
Get demoted, suddenly the games are more evenly matched, I get less players raging constantly, and overall they are just more fun.
So why can't we have games that are more statistically balanced, and less "you have to carry or get demoted" type of games.