@leocg First of all, thanks for your reply!
You could still give the option of a complete full screen. However, nowadays we have more and more websites that look like apps, like online trading platforms, google docs/sheets, this very forum! They demand a more useful screen space. But when you open them in a complete full screen by pressing F11, you totaly lose the command buttons, demanding you to return to normal mode. The way I described, you wouldn't lose the buttons (any buttons!). They would only be hidden.