I think you have a point, and I agree about this kind of complaint for screencapture where there are APIs on Wayland so you can't point at X-based software that didn't port and say "it's broken"!

However as far as I am aware there is no proper key-capture or key-inserting API in Wayland. There are hacks (IMHO) like bypassing the compositor and reading the events directly but we are still missing a well-defined API that is supported cross-compositor.

I am fine with GNOMEs very limited keyboard shortcut support but I definitely agree that this is a step down from what we had on X.