I have positive proof that Riot will screw over people with good win rates in ranked.
So this season I was going to change how I did ranked. I was going to play smarter and better, even looked up how to know when to dodge if a game if you end up with a bad team comp or a teammate who you think will drag your team down. I had worked like crazy to get a 66.5% win rate through 56 games, and then Riot decides to start screwing me over with teammates that will lose games. In the last 15 games I have gone 2-13, NO MATTER WHAT I DO I GET SOME FEEDER!!!! I lost 10 of those in a row, no matter what I did. There were also games in there that I lost but I can only think of three. I did have an mmr of plat 5 while in gold 3 but that is ruined now.
So now I have learned that Riot wants to forcibly keep players down if they start doing good and will pair them with teams that have a very good chance of losing.