Don't forget that there are hundreds of distros, that may or may not use
different versions of the same libraries. As an example, Ubuntu uses
Gnome3, but not Gnome Shell, Linux Mint, which is based on Ubuntu uses a
fork of Gnome2, Fedora uses Gnome3, with Gnome Shell. There are distros
out there that use KDE, LXDE, and others.
Do you think software developers out there can see a return on the
investment of coding for all of the different versions of DE?