What was really behind the push to get everything browser based in the first place? Is this all to make everything cloud based, software as a service, or did some exec see a demo of Windows 8 and think "web is the future" and over-rotate?

The least cynical argument is internationalization. Rendering engines already implement robust text layout when multiple languages are involved, so it makes sense to leverage it. The more cynical argument is that it's easier to find web designers than desktop UI designers. The more-cynical-still argument is the one you said.

Turns out the browser is an incredibly sophisticated and highly performant layout engine that works on almost every platform out there. Native UI frameworks are always going to be more efficient and let you access more of the hardware, but it's more expensive to maintain 2 or 3 separate codebases.

The push is that web developers are easy to find, and native software developers barely event exist anymore (and if they do can get paid to work on things like trading software, though web is even picking up there!).

Microsoft don't even _have_ a reasonable desktop UI stack, having been through at least 4-5 which gained minimal traction before being abandoned. The last successful one was Windows Forms, which is what I'd pick up today if I ever had to touch Windows again.