The Mac behavior comes into play with “document” apps (text, image, or whatever). You have app running and a document open. You can then close that document and

The Mac behavior comes into play with “document” apps (text, image, or whatever). You have app running and a document open. You can then close that document and open other document. You don’t want the app to close when you close the document. Conversely it works well with apps that reload documents when they restart. You just close the app without closing the document. When you restart the app, the document is loaded and state is preserved. This is not about a desire to keep apps running in the background, though there was some advantage to that in the old days when starting an app did take considerable time. Leaving it running in the background for some shortish time made some sense. Non-document apps (like control panel) generally close when the window closes because there is no document to open and close. They usually only have a single window, anyway, or at least not multiple independent windows.