As I understand it, it's not a technical problem, rather a social one first off: you can build it but it'll be "empty" compared to all other options out there, even if it's technically superior to them. Network effect and all that.

There's also a technical problem you'll have to contend with: bots and scammers... so many bots and so many scammers.

Totally. It's a very boring part of this that one would have to contend with.

I kinda feel the same way about Facebook. Groups, events, marketplace are amazing for community building. But it's just so hard to compete with Meta.