To me the benefit is not to have a single application that works both with a touch screen and a mouse/keyboard. Rather, the benefit is to have a single filesystem that I can access with both touch screen apps and mouse/keyboard apps. This way I could for example create a grocery with a mouse/keyboard, then take my phone and check items off with a touchscreen. There are lots of things we rely on the cloud for that would be better served by a "convergent" environment imo.