Sports subreddits are a notable exception imo. While they might get a bit silly, r/cfb, r/nba, etc. are so much better than Twitter or any other public forum that losing them would be pretty awful.
I only follow motorsports so the only sports subs I'm on are motogp, v8supercars and formula1.
The F1 subreddit (over a million subs)is one of the absolute worst places on the internet for any kind of discussion. It's totally dominated by The Hive Mind, dissenting opinions are absolutely unwelcome and the top posts on every single post are low-effort jokes, usually jokes that have been told a thousand times before. It's awful.
MotoGP (250k+ subs) is better, but still suffers from similar problems.
V8Supercars is quiet, but the discussion is of a far higher quality.
Subreddits generally undergo twinkdeath between 100k and 1m users. Once enough people know about the sub they tell all their snoo friends and pretty soon itβs just a hivemind and memes and funny quips. Watched it happen to a lot of tech subs.
The exception is subs that lean heavily into over-the-top curation which is also its own special kind of groupthink hell imo.
/r/formula1 is really hit or miss. I wouldn't say it's as horrible as you make it out to be, but the pervasive groupthink of the sport as a whole (whoever is on top needs to be knocked down a peg, Liberty Media sucks, whatever) is certainly strong there.
