@tbernard the #Fedora #flatpak repo has a fair deal of #Plasma packages in it, and that's probably because the Fedora community has been porting desktop apps over to it.
I have a cynical take though. I believe that #designers and #UX experts gravitate more towards #Gtk/ #Adwaita because it is more modern. Plasma/ #Origami has come a long way, but is still not as enticing as Gtk/Adwaita. This becomes a little barrier to entry in of it self, IMHO. It also means there is more Gtk #abandonware.