I'm not convinced that convergent UI works either. The needs of desktop and mobile just differ too greatly.

That doesn't mean that the two can't be served by the same UI framework, but at minimum you need two sets of widgets and separate desktop/mobile layouts in order to not either make the desktop experience dumbed down or end up with a mobile experience that's awkward to use with touch.

The padding and control size in GNOME feels completely goofy on a desktop machine for example and reduces the usability of 12"-13" laptops with how much space is eaten up by blank space.