Hacker news is a web application, with a client-server architecture. Indeed would be impractical to replicate with the file system model.
Still, I think it would be useful to have standardized hypermedia documents. It would allow for content that's naturally multimedia to be much more easily handled and distributed. I find it super weird that we need to create a 'website' just to have a multimedia, responsive document. It practically must be hosted on a server because nobody sends HTML around. Mind you that I used the file system just as a metaphor for what an offline-first hypermedia document model could look like.