Basically, X11/Xorg doesn't isolate programs from one another. This is horrible for security since malicious software can read every window, as well as all the input from mice and keyboards, just by querying the X server, but it's also handy for screen reading software, streaming, etc. Meanwhile, Wayland isolates programs in their own sandbox, which prevents, say, a malicious browser tab from reading all of your keyboard inputs and logging your root password, but also breaks those things we like to use. To make matters worse, it looks like everyone's answer for this and similar dilemmas wasn't "let's fix Wayland" but "let's develop an extension to fix Wayland" and we wound up with that one fucking xkcd standards comic that I won't bother linking because everyone has seen it a zillion times.

ETA: Basically, my (layman's) understanding is that fixing this and making screen readers work in Wayland is hard because the core Wayland developers seem to have little appetite for fixing this themselves. Meanwhile, there's 3-4 implementations of Wayland that do things differently, so fixing it via extensions means either writing multiple backends in your program to do the same damn thing (aka a giant pain in the ass) or getting everyone to agree on the same standard implementation (good fucking luck).

It won't in 24.04 because Cosmic doesn't support anything else