Unpopular opinion: any social network, no matter how it’s architected will become terrible past a certain size. Perhaps some architectures will have different “maximum tolerable sizes” than others, but all will become intolerable once there is a large enough user base.
More users, however, means more ad / tracking revenue, so these two ideas will always be at odds.
Dealing with opensource projects via discord is a nightmare. One I use regularly decided to escape the walled garden and move to github discussions and it's been such a boon for search. Discord is a repetitive nightmare of doing support I don't know why projects use it.
The discord server still exists but questions generally don't get answered as much or if they do it's usually a link to github discussions.
There is/was already a social network for that - Ning.
Back when social network platforms became A Thing they adopted OpenSocial - they had a news feed, notifications, etc - but each social network was completely isolated. I haven't taken a look at Ning since I worked on social networking apps about 12 years ago, so I have no clue how they've evolved since then.
More users, however, means more ad / tracking revenue, so these two ideas will always be at odds.