Reminds me of .plan files from back in the day.

This seems less "decentralized social network" and more "html-less www with extra steps," especially since it's only going to allow socializing between the specific types of people who fall within 3 very specific Venn diagram circles who 1) use emacs, 2) use org-mode, and 3) want to go through the trouble of hosting their own section of the network.

What does it solve compared to a normal plain HTML blog?

This looks like a bad hybrid between RSS and Markdown. Am I missing something?

Just last week I was fiddling around with a tangentially related idea. I made some modifications locally to my setup so that when browsing a .org file in eww, org-html-export-as-html would render it in the buffer as HTML directly. eww doesn't really support much styling via shr, so I was working on adding some basic css parsing to expand the range of expression for an org-based blog approach.

Many people export their org file based blogs to HTML and then publish them, but my thought would be to skip that and instead provide a path for eww to directly render org files, cutting out my html export stopgap.

This sure is a social network for a very small and specific set of people.

We kind of already have groups in Gnus... I even messaged one group, like twice in my life.