As has been said countless times (but I’m not sure if to you) is that they don’t “force” 50%. They use MMR to predict a 50% match and use the result to update the MMR of the players. Which makes all the difference. The longer version is at How Competitive Skill Rating Works (Season 10). See especially Summary → Summarize matchmaking, rating, and progression for me and Popular Myths → Matchmaking pushes a 50% win percentage using broken criteria.