Plan9 allows for implementing file servers in user space and exporting a whole file tree as a virtual "folder", so it's really more of "everything as a file server". No different than FUSE, really.
And as Feynman said, you don't truly understand a thing until you can teach it. So that leaves us in a weird predicament where the biggest proponents of Plan 9 apparently don't understand Plan 9 well enough to teach it to the rest of us.
"Plan 9 praisers who don't actually use Plan 9" have a tendentious way of speaking, that's actually a lot like "AI slop", that Plan 9 users can instantly recognise. Telltale signs include speaking about Plan 9 in the past tense, and a belief that with Plan 9 you can somehow just strap all your computers together to get more performance or something. Because "you have 9P".