Think less about time sharing and more about using all the computers you own together.

You would have a netbook with no compute power as your UI sitting on your couch. You could connect to your beefy desktop to do all the computations for your video editor or playing a game and never have to be sitting at your desk.

You could also have a big file store device with lots of drives to store stuff.

We can do some of this now, I ssh into my desktop from my couch and have a NFS in the basement. But they all operate as separate devices that i have to really work at getting to operate together. Plan9 was designed where you'd just pick devices off of the network and the tasks operated normally. Pick your video card, local or over the network to the beefier GPU.

The networking stuff probably won’t do you much good if you do not have other Plan 9 systems to talk to, but the GUI and window manager and editor, those also operate in this way that’s 100% different from anything else that exists. To me the networking and the way the file sharing works are probably the most interesting things, so IDK, you might be partly right.

I think this might be part of why it hasn’t caught on at all is that a lot of the stuff about it that works better only works better when talking with other Plan 9 systems, of which there aren’t really any.

I'd say so. It was built to be the sort of general purpose OS that Linux is, only taking into account everything we've learned about how to make a good operating system from the whole history of *nix. And Plan 9 is newer than Linux in the sense that its first release came out after the Linux kernel's first release. X11 has even been run on Plan 9 with adapter layers.