Xorg also doesn't prevent you from using an application that does have these functions. Wayland does prevent you.
> but it's perfectly possible to write without any changes to the compositor (e.g.: the compositor provides the necessary APIs for thi).
The necessary APIs don't exist, so it isn't possible to write the extra functionality without changing the compositor.
Honestly, I don't understand why anybody defends Wayland at this point. It's been, what, ~~six years? Six years~~ FOURTEEN FUCKING YEARS we've been telling you that we want to be able to use our screenshot and recording applications and that removing functionality that we use day-to-day wasn't acceptable. Are the Firefox devs the same people making Wayland? Is that why they're so unresponsive to user needs?