I think it's mostly frustration when Apple leverages the fact that you can't (legally and without a bunch of extra & ongoing work) run macOS on non-Apple hardwa

I think it's mostly frustration when Apple leverages the fact that you can't (legally and without a bunch of extra & ongoing work) run macOS on non-Apple hardware to push changes people don't like to the hardware, or to charge plainly absurd prices for same. [EDIT] actually I think it's similar to the reason some people get pissed off over over perceived mismanagement of fiction franchises—if anyone could tell a story in a given "universe" they probably wouldn't care much if some of those stories were (from their perspective) terrible or misguided or misunderstood and misrepresented the characters or world or whatever, but when only one entity is allowed to tell those stories and define the direction of the "universe" it bothers certain fans a lot if they get it "wrong", and in fact almost any given piece of related media is likely to make someone unhappy in a way and to a degree they wouldn't be if that were just one of many options, rather than the only option. [EDIT EDIT] and in both cases the problem is monopoly control over a very particular product. Yes you could watch other movies or use another OS, but you'd much rather that one simply be better (in your opinion) so you could stick with it or so, in sticking with it, you'd be more pleased with the product, because it's your favorite.