I think, weirdly, I have a harder time finding communities around that sort of thing now. I mostly read HN. Where would I go to find something like HN for, say, sustainable living? woodworking? cycling infrastructure? A lot of it is, if nothing else, subsumed in to a Facebook group, or a slack group, etc.
The best I've found is small subreddits. Which is not ideal, because discovery is a giant PITA. Much like the split between /r/trees and /r/marijuanaenthusiasts (the /trees subreddit was first founded by people who were talking about weed, and people who wanted to talk about actual trees were a little nonplussed at the whole thing, thus creating /marijuanaenthusiasts and using it for tree-talk) most of the better communities are using a name that is not immediately obvious, so that they aren't oversaturated from the get-go.
The bigger problem with reddit, in my experience, is that 95% of the comments on any given post are pure garbage filler. Joke chains as far as the eye can see.
HN is also quite bad to have long-term discussions about a topic, and suffers from the same constant rehashing of topics happening on reddit. It sort of works for news and random individual articles, where there aren't necessarily longer logical threads, but that's not what many communities need.
E.g. a typical comparison between forums and reddit: A hobby forum often has a "I just bought X" megathread or two, where people post new things they've bought and want to share their excitement about, but that don't warrant a full thread. On hobby subreddits, a large amount of the threads can be "I just bought the thing everyone always recommends and everyone has seen 20 times this week, can't wait to use it!". Similarly, what would have been a single post on an old thread in a forum needs to be it's own thread on reddit, loosing context and making search harder (even if people try to link other relevant threads). Which in turn leads to more repeat questions etc.
Hacker news is 30x worse because you don't even see replies to your comments so the fire and forget mentality is very strong. Also very discouraging to reply to older comments because once it gets over a day old its likely even the person you reply to wont see it.
Moderation is definitely key to dealing with that issue.
For me, as with HN, I don't like the inherent stress of commenting on submissions before they fall off the front page. The earlier one comments, the higher the chances of getting eyeballs/responses. After that short ~24 hour window, people may still read the comments, but submitting new comments seems futile.
As opposed to older "style" forums, even today, threads often stay open, allowing people to post months or years later to revive "dead" threads.
The two-hour edit window and rapid falloff on HN are two of my least-favorite aspects of discussion on this site. It is almost a daily occurence I'll come across something interesting here, get ready to type a contribution to the conversation, then realize that it's too late, and it won't be read. It is a little demoralizing.
I'm sure this approach also eases the moderation burden, and I'm pretty impressed overall with how dang handles things. So maybe it is a simple workload necessity. It does strike me that HN could be quite a bit more if these two restrictions were loosed.
Most SO sites have too many moderators squelching any attempts at constructive, and deleting the unique as duplicate. Like Wikipedia it's become incredibly hostile to newcomers.
Do you have any advice on finding it?