Some people do a hybrid approach. A public forum/board to share content, with some rules. Then another private server for a smaller group of friends to share anything.
You can also create a Tor Hidden Service.
You will never get that kind of activity on a Tor service. If you look at the more obscure, older fetish-related networks which often still have active IRC channels and such you'll notice that a large portion of people there are quite techy.
I don't think that's true for the wider kink community at all, it's just that the barrier of entry & discoverability of such communities will exclude the less techy folks.
And exposes you to all kinds of problems to care about including DDoSes, pwners, lawyers, hardware failures etc.
> You can also create a Tor Hidden Service.
So (I feel sad about this but this is how it seems) almost nobody will ever find it, but child porn lovers and other kinds of ultimate weirdos will and you will have hard time banning them.
I've seen twitter and ao3 mentioned the most for replacement.
GNU Taler seems to be that answer, if it would ever actually launch...
https://news.ycombinator.com/item?id=18529764 https://cryptosumer.com/2018/11/24/free-software-messiah-ric... https://taler.net/en/index.html