Why would you want different UI framework for each screen size/input device type?

Seems silly to have one set of API's for small touch devices and a completely different one for large mouse-driven devices. Shuts the door to large touch devices and small mouse-driven devices.

iPad Pro is already awkward. At that size, a mouse would be nice, along with lots of other desktop UX paradigms.

> What has Microsoft shown with their multi-paradigm direction?

Seems to be working. Windows Shell, modern Office, Edge, and Xbox dashboard are all using the same UI framework.