Earlier quoted context omitted.
But there is no single "Linux Desktop". If these people would contribute to e.g. Gnome instead, they might help improve Gnome but they couldn't realize this idea. Personally I think there is little benefit to having one single Linux desktop that is equivalent to Windows or macOS, just with a different theme and a different kernel. Desktop Linux is about choice (TM).
Well that is a good idea. But it has a problem: dev and ux capacity. When you try to make 20 different than you split your force into 20 different projects. Apple and Microsoft do not have this problem and will therefore always lead the pack.
Sure, for different hardware (RPi, Tablets, PC, Mobile etc) different distros/DEs make sense. But for a single similar hardware, (PC for example) I never understood why distros like Manjaro and KDE neon are separate. Wish those teams were together and built a kick-ass serious competitor.