Classic MacOS can't really be said to have a kernel, as it had no privilege separation and no security whatsoever; user applications ran with full access to the

Classic MacOS can't really be said to have a kernel, as it had no privilege separation and no security whatsoever; user applications ran with full access to the hardware, and used cooperative multitasking instead of being preemptable. The QuickDraw routines were in ROM but the only difference that made is you had to modify a jump table instead of being able to overwrite them directly. (All of the above supports your point; it's just that the Mac went further than you implied.)