Having a key reserved for OS level actions means you can create your own shortcuts and macros based on it without fear of it conflicting with each app shortcuts.

Since operating systems also don't change often nowadays there is also seldomly any conflicts when a new system shortcut is added.

I also love good old Meta + left click/right click drag for moving and resizing windows in linux.

It may be ten uses, but it's ten uses I use constantly throughout the day.

You must not use MacOS. Command gets used all over the place, even during editing. And in Emacs it gets used as Super, which opens up some options.

Even just the window management category is more than ten uses. And it is unlimited uses, as you can assign additional shortcuts however you like.