This sounds nice on an abstract level but how do you implement communities with that?
I mean, if I don't want my regular persona connected with my Chuck Testa erotica that can be solved by having two domains and two POSSE stacks. Costs money but is easy enough in principle.
I might be perfectly fine with the same persona/domain being associated with both my work (Befunge enterprise software development) and my more normal hobbies (interpreting D&D characters as rappers). But the people interested in the hottest developments in two-dimensional ERP software will probably not be interested in my new article on how ill Illmater really is.
So how do I separate these? Tags don't seem powerful enough for this task; if I have to tag every article with every group of interested people then most posts will drown in tags and careless use of a tag might lead to the equivalent of posting an emphatic affirmation of LGBT rights to a version of Truth Social where the only form of moderation consists of raiding the offender's blog.
For that matter, how do you moderate POSSE? I can't come up with a reasonable way to do so.
In the end it seems that it's a really cool concept if used by renowned tech evangelists and just about nobody else.