Resizing windows is a weakness of Mac OS. It mostly retains the original fully manual method of dragging the edges of individual windows which is a fiddle process. There are some methods like mentioned in the original post, but that is about it. For that reason there are dozens of third-party tools, many free, that people use and like for their particular ways of working. It would be nice if Apple were to look at these and implement a basic verion of one or more of them in the OS.
The “stoplight buttons” on windows are part of a very opinionated solution to window management that works from some people but is a complete mess if you don’t like full-screen apps. I would prefer if we had the option to convert the full-screen button to a maximize window button. Double-clicking on the window header is close.
The other thing that Windows users complain about it that closing a window doesn’t close the app. That one is just a confusion because they are used to how Windows windows. The Mac OS convention of keeping the app active is not wrong, it’s just a different approach and the kind of conceptual change that users need to make when they switch OSs.