Except Mac OS 7-9 (media production because a patched Mac OS 9 under a G4 is beast) and DOS (expensive ad-hoc industrial hardware), most computer/OSes aren't used to anything but retrogaming/retroemulation except with some niches with the Atari STE/FreeMint communities.

Well… in my house the only use the Windows box gets is gaming and I wouldn’t call it “disused”. It’s a horrible kludge, but not “disused”.

By far the most fun computer in the house is the C64 Maxi Commodore recreation. Endless hours of fun.

So somewhere out there there are people sticking to Mac OS 9? Or earlier? That's rad

Yes because the input latency on os9 under a G4 it's almost inexistent. There are unnoficial patches for media production:

http://macos9lives.com/

http://macos9lives.com/mac%20os%209%20lives_005.htm

I am more like a Void/OpenBSD guy with Unix and CLI tools, but people keeping old machines being useful it's always good.

Unix is wonderfully useful. I can run my applications on the Linux server in the shed and have the GUI on my laptop using X. I can do the same from a G3 iMac or an IBM RS/6000.