The HN crowd always suggests technical aspects they want out of online communities. No one cares about that crap.
Instead, what about online communities that: don't incentivize shallow responses, don't incentivize like or karma gaming, do encourage great content, do encourage participation to a slightly greater degree than most places where 80% lurk.
I think good online communities are actually small. At a particular point in time, as population scale goes up, you don't find people familiar anymore and as a result no one has a reputation. The site has a reputation.
How do we create good online communities? Someone has done this homework, yes. At least, I believe there are studies out there somewhere which talk about the threshold of people that we can recognize with any meaningful context.
I agree with everything you're saying, but what you're describing isn't a social network. It's a private, invite-only community and those have serious limitations when compared to an open social network.
IMHO, HN and Reddit are at their best when random people whose opinions you wouldn't ordinarily hear from decide to comment. For example, It's pretty common here on HN for open source authors to chime in on threads where their product is being talked about and answer questions. On Reddit, you'll occasionally get highly detailed comments from people with hands on knowledge of the topic being discussed. One that stands out in my mind right now is when an LA city planner commented on a thread about building high rent condos vs building low rent units. He laid out all of the city building codes around new buildings and why the finances don't work out for the low rent units. It was one of the best comments I've ever seen on the topic on Reddit and it would never have happened had the subreddit been closed off or invite only.
Of course, then the problem becomes how much crap you have to sift through to find that nugget. But, If you deleted all the crap as "shallow responses", would the lack of posts still attract those nuggets of great content? I think a high comment count and a high karma count actually attracts higher quality commenters because there's a perceived greater chance a lot of people will read it.
The only solution I can think of is to have a lot of moderators constantly auditing threads, marking the high quality comments so they stand out at the top and outright blocking or banning anything too egregious. Crowdsourcing doesn't work for this because it gets weaponized and/or abused.
Ultimately, what makes or breaks a social network rests entirely on the decisions the mods make about what kind of content they want on their site.
Limits and costs. You can only connect to 150 people. No celebrities / influencers. You can only write X messages a day, and copy paste is disabled. You cannot share for free, got to articulate at least 50 words. The reader got to click the share link if they want to see the original content. No one click karma, let people write 50 words or more if they want to express their feelings. Concession: Voice dictation, typing 50 words on a phone is too expensive.
Instead, what about online communities that: don't incentivize shallow responses, don't incentivize like or karma gaming, do encourage great content, do encourage participation to a slightly greater degree than most places where 80% lurk.
I think good online communities are actually small. At a particular point in time, as population scale goes up, you don't find people familiar anymore and as a result no one has a reputation. The site has a reputation.
How do we create good online communities? Someone has done this homework, yes. At least, I believe there are studies out there somewhere which talk about the threshold of people that we can recognize with any meaningful context.