Why not have single generic "Atomic" version and provide desktop environment as selection during installation? Like Debian does. Or is DE so tightly coupled into images, that it cannot be replaced?
Fedora immutable distros are image based, so yes, the base system is a pre-made unit, over which you can layer minor packages but not something as extensive as an alternative DE. Hence so many spins, as well as separate versions for stuff like Nvidia cards, Asus machines and so on.