There were a few posts in the past that were focused on RSS based social media.

https://news.ycombinator.com/item?id=33975082

https://news.ycombinator.com/item?id=28645871

Most of them focus heavily on consumption and redistribution. It still requires you to own a source of truth (eg blog) but none of them solve the interaction problems (eg how to leave a comment or have a conversation)