Well, on Windows and Linux, the maximize button almost always works, where on MacOS it does something, but after using one for work for 7 years, I still don't know what it's supposed to do. I'm not a big maximizer though, big desktop monitors and maximized windows aren't good for me.

Well, Windows and the most common Linux DEs make it easy to maximize windows, while on MacOS there's only a full screen button by default (which is not the same and most people probably don't want). My anecdotal observation has been that Mac users end up manually resizing windows often, to increase size to a large portion of the screen when necessary - but they don't fully maximize windows.

That's actually an interesting question, I'm not sure if anyone's looked at it. It probably depends heavily on your window manager of choice (some of them take the choice out of your hands).

For my part, I don't use a tiling window manager, and the only things I maximize sometimes are VM displays.