There is a legion of people who think macOS has maximize functionality. They would activate green zoom button and if zoomed size happens to be smaller than whole of desktop's working space (e.g. Safari), complain that maximize button is bugged.

In fairness, macOS' behavior is less predictable than maximize, insofar as what happens when you press the green button depends on the contents of the particular window.

Whether this is a problem or not depends on one's own particular tastes in OS behavior.