> Most modern software is built upon libraries that support either Wayland or X (assuming it has a GUI), so they should be blissfully ignorant of whether their application is running under Wayland or X. Most of the outliers are older programs that are built on top of libraries that haven't been updated for Wayland, but most of those programs will work under Wayland assuming that xwayland is installed.

That's true of software that just receives input from the keyboard and mouse and sends output to the screen, but for anything that does more advanced stuff than that, e.g., xrdp, there's often either no way at all to do so in Wayland, or doing so requires custom code for every DE instead of being able to write it once and having it work everywhere.