I’m convinced that some of the toxicity is tuned to your own contributions. I’m almost 40 and I still play League 8-10 hours a week.
Almost all of that is tipsy ARAM games, and considering I got my toxicity out years ago I find that, given I’m always positive and having a fun time, I solely run into others that are positive and having a fun time.
People might underestimate how much self sorting that game does based on behavior in their algorithms.