BTW there was a nice idea behind the only close button in early GNOME 3. Apps were intended to save the state on exit, so one doesn’t need to minimize windows, they can close it and reopen at any time and see the exact content of a window. But GNOME completely has failed to deliver that idea.
What makes things worse, there was no clear way to keep apps on the background when the main window is closed. It was seemed as antifeature. But that was a different world where weren’t so much of internet service applications running on the background 24h a day. Now there is a background portal but with quite minimal support in the DE.