The difference is that it is not a "standardized" OS interface. Rather it's a complex layer on top of operating systems offering dumbed down and less performan

The difference is that it is not a "standardized" OS interface. Rather it's a complex layer on top of operating systems offering dumbed down and less performant versions of what is available all of which is interfaced by a dynamic and not so performant language. If it was something like a modern POSIX I don't think you'd have much complaining. But it's a lot heavier than that.