Earlier quoted context omitted.
Drivers. Apple likes the control over the hardware and software, and packages all of the drivers needed to run macOS on any blessed instance of Apple hardware currently supported (and maybe even ever created, since Intel). If you wanted, and I have done this before, you can clone a Mac made HDD and boot it from any other Mac you can get your hands on, and other than the hardware swap it's basically a reboot. If Apple…
If it's for developers they don't have to guarantee it. I'm happily running a hackintosh right now. If they made it a little easier we wouldn't have to do weird hacks to spoof hardware ids just so messages work.
This would only be true in a world where Ars Technica, The Verge, and other publications did not exist.
Apple would suffer from poor performance reviews for any sort of driver issue. Plus, "not guaranteed to work" is the opposite of Apple's ethos, which is "it just works."
Apple has made it easy enough for hackitoshes to work by being lax with people running MacOS.