This is... I don't know. I don't get why I would care to sling SQL over a file system versus a network socket.

I mean, Postgres could offer an SSH interface as a dumb pipe to psql to just have you push text SQL queries in your application. But it doesn't, it offers a binary protocol over a network socket. All the database engines have had the same decision point and have basically gone down the same path of implementing a wire protocol over a persistent socket connection.

So yeah, I don't get what doing things this way would give me as either a service provider or a service consumer. It looks like video game achievements for OS development nerds, "unlocked 'everything is a file'." But it doesn't look like it actually enables anything meaningful.

How would you connect to Postgres in 4 lines of shell normally? How would you do it for a rest api? How about any other systems?

For Plan 9, it's all the same, all using the same interfaces, with little library glue.

Opening a window, and running a command in it? Similar interfaces. Adding LSP to your editor? Got it, you mount it and write to the files.

Universal shared conventions are powerful.