Apple could have killed them ages ago, by allowing their OS to be licensed on any processor, and include a state machine rom with each licenced copy, said state machine being a soldered un-crackable dongle, so that Apple gets ~~$100 per copy - they would slay Microsoft.
As it is Apple clings to their walled garden = dumb, but Apple = richer than me, so what do I know?
I think you forgot about the Mac clone era. Unfortunately, the third party clones were horrible. At the time, discontinuing the licensing of Mac clones was the right thing to do. All they did was tarnish Apple's image.