Re: to the extent that Microsoft deserve criticism? (@Tinker Tailor Soldier)
I'm unclear who you think is rewriting history — essentially both the PC and the Mac came from companies that understood protected memory and MMUs perfectly but choose to omit the hardware for cost purposes. There was an MMU in the Lisa, there wasn't in the Mac. There was one in any number of IBM machines going back decades, there wasn't in the PC.
The history of Apple's multiple subsequent internal OS development screw-ups is interesting but quite distinct from Microsoft's errors. The stories start similarly but Apple get to the point between 6 and 7 where the resources were such that they could have afforded just to run multiple instances of 6 simultaneously and preemptively to multitasking properly with memory protection on those devices with MMUs, but instead they double down on cooperative multitasking and spend the newly spare resources on rewriting a bunch of things in C. After the PowerPC move they have a full preemptive, protected memory handling nano-kernel which is used to run the existing OS. For quite a while large parts of the stack remained in 68000 code and just ran through an emulator — they spent engineering time getting the emulator down small enough to fit entirely within the processor cache because it was a more effective way to transition than dealing with the OS proper.