That’s one of the huge problems with Wayland. The core protocol is super minimalistic so it falls to each and every individual app to (re)implement everything: accessibility, clipboard, keyboard, mouse, compositing etc. etc.
The fact this was done in the name of security is a solution looking for a problem. Inter-window communication was never a stringent security issue on Linux.
It’s like advising people to wear helmets in their everyday life. Sure, in theory it’s a great idea and would greatly benefit those who slip and fall, or a flower pot falls on their heads, or are in a car accident and so on. But in practice it would be a huge inconvenience 99.99% of the time.
The largest part of all Linux apps out there will never get around to (re)implementing all this basic functionality just to deal with a 0.01% chance of security issues. Wherever convenience fights security, convenience wins. Wayland will either come around or become a bubble where 99% of Linux userland doesn’t work.