Those "incredibly bespoke communities" are almost entirely people posting images of a professional/elaborate project, and then asking for feedback in the form of "hey you guys this is the first thing I've ever made please give me some feedback but go easy on me OK?"

It's a massive circle jerk and echo chamber of regurgitated opinions. So in other words: exactly like the rest of Reddit.

And it's also people posting reviews of some tool, or long tutorials on some technique, or answering questions from beginners, or collecting a FAQ with the basics/intermediate level of learning of a hobby which becomes an intro manual of what you probably need to learn as a foundation.

It can be also a massive circle jerk but if that's the only thing you can see from niche subreddits you are coming into this with a massive bias and ignoring the good parts, and these good parts are missing from most of the rest of the web.

I feel that your opinion is the same, just an attempt at a massive circle jerk about how terrible reddit is. It is, but it's also not and if you sincerely can't see how useful reddit is for a wide range of hobbies it's probably because you're a little myopic.

If that's your definition of circle jerk then basically you can't have a conversation with anyone, on any medium.

A conversation is always at some level about voicing your opinion or showing something you've done or bought and basically ask for feedback/reactions.