It is a bit moribund but there are some newsgroups that are alive. It's full of spam, trolls, and obnoxious contrarians, but you can post about whatever you'd like, receive replies for whomever, and never have to deal with upvote politics or comment pile-ons.

One newsgroup I recommend is `comp.sys.raspberry-pi`. It has a pretty high SNR and is quite active, especially in comparison to some other groups on Usenet.