A lot of developers are very concerned about UI/UX. Linux just makes it impossible for them to do so. But even without them caring for UI/UX, the proliferation

A lot of developers are very concerned about UI/UX. Linux just makes it impossible for them to do so. But even without them caring for UI/UX, the proliferation of DEs, even with common UI toolkits in the Linux world means they spend a lot of time and energy working on bugs that are not true bugs but are artifacts of a UI theme that the developer did not consider while developing their app. For example, it's almost certain that the unified tooltip in COSMIC will lead to bugs complaining about how users are unable to drag the window by clicking on the chrome. In this case it would be fairly easy for a dev to close the bug because this is such a prominent and obvious difference in COSMIC. But there will certainly be other UI differences that will not be as easy to pin down to being the result of COSMIC's UI changes, and will not be as easy for devs to close.