I mean that at an API level, you can't manually select what you want to capture whether that be a particular screen or a single window. You have to send a dbus

I mean that at an API level, you can't manually select what you want to capture whether that be a particular screen or a single window. You have to send a dbus message to the DE which will then pop up its own UI to select the thing you're going to share. So lets say you have some cross-platform UI code for screensharing with an OS abstraction layer that has functions to get a list of potential sources (perhaps with previews) and another that starts screensharing with a particular source. That particular design works fine on Mac and Windows (except in the UWP ecosystem, but no one cares about that) and also with X11, but not with Wayland. So now it's not just about having another implementation of your OS abstraction layer for a new capture API, it's also about mucking around with the UI flow. In the grand scheme of things, this is not a huge deal, but it makes supporting the API kind of a PITA.