GNOME and KDE are desktop environments at the root: they may have built other stuff on top of that, but KDE at least is still interested in being useful on a desktop, and at least partly driven by the needs of desktop users. That's good, because it's their *existing userbase*. GNOME seems to have forgotten that (though GNOME has long had a wide streak of developer contempt for users, where 'users' are defined as 'anyone not a GNOME developer': so maybe this is just an existing tendency intensifying into an outright pathology).
(FWIW, I consider laptops to be 'desktops' in this respect: the needs of laptop UIs, other than a few extra devices and lots of hotpluggability, are very similar to those of desktops. Tablets, though, are wildly different.)