I can definitely relate! I think my biggest problem is that you have to reply to someone very fast and with a very short amount of text. No one will read your comment if it's long, and if you aren't fast enough, someone else will have replied and then no one will see your comment. This quick+short combination results in people making really shitty quality arguments, and then making a long, good-quality argument reply to them is just not worth it. So then, the comments just spiral into ad-hominem attacks and are generally just a hate-filled mess.

I also agree with your sentiment about subreddits and the hives mind mentality it breeds. This is slightly better in the small subreddits, but even then sometimes they'll have this issue (for example, /r/linguistics is filled with generative grammarians and expressing that you're against that theoretical framework never ends well).

I've only been on Hubski for a little bit, but I'm liking it very much! People seem generally nice and open-minded. Whether this is because of the structure or just the size of the community is unclear to me though.