The idea is that you should consider the area around the notch to be extra, and not part of the normal screen. Show your game on the rectangular part of the screen, and use the extras for stuff that doesn't need the whole screen, like time, date, notification count, menu, whatever.
Having just the rectangular screen means not having the option of making those things visible, or having a smaller screen.
Why? Unless I am running a full screen app the notch gives me more screen space. Remember that the mac have the menu bar on top of the screen at all times so the space is not available for normal windowed apps.
I hide my menubar by default. I like using my space for stuff I'm actively looking at.
I was watching someone code in vim on a new mac the other day and the notch covered part of the first like of their editor! Like how does this not completely break you as a human. Maybe I'm a little OCD idk.
Isn't there just like an option to change the resolution and fix this? Apple should really have a "disable notch" mode.