A good paper giving a concrete example of all this is "A fork() in the road", where you can see how an API just like fork(2) has an absolutely massive amount of

A good paper giving a concrete example of all this is "A fork() in the road", where you can see how an API just like fork(2) has an absolutely massive amount of ramifications on the overall design of the system, to the point "POSIX compliance" resulted in some substantial perversions of the authors' non-traditional OS design, all of which did nothing but add complexity and failure modes ("oh, but I thought UNIX magically gave you simplicity and made everything easy?") It also has significantly diverged from its "simple" original incarnation in the PDP-11 to a massive complex beast. So you can add "CreateProcess(), not fork()" on the list of things NT did better, IMO. And that's just a single system call, albeit a very important one. People simply vastly overestimate how rose-tinted their glasses are and all the devils in the details, until they actually get into the nitty gritty of it all. https://www.microsoft.com/en-us/research/uploads/prod/2019/04/fork-hotos19.pdf https://www.microsoft.com/en-us/research/uploads/prod/2019/0...