I believe the original mindset was that the OS only runs on Apple hardware, the purchase of the hardware paid for the OS.
Back in OS X Mountain Lion (2012) OSX was a separate product. I had a Macbook but bought the installation disk (OS) from a online store, because it wasn't bundled. Then suddenly they made it 'available to download from the App Store'..
Nice idea but in order for that to work you need to cut people off at some point like Windows used to. Otherwise you'll be giving out software updates gratis in perpetuity.
They do cut people off. macOS 13 doesn't run on any hardware from before 2017.