Except that doing it once wasn't enough.
8.0 had separate models for phone, tablet and desktop.
Then 8.1 unified tablet and desktop, while keeping phone apart for view code, so UAP was born.
With Win10 everything got merged together as UWP and the whole One Core marketing happened.
Then since the WinDev team had some score to settle, C++/CX was deprecated and replaced by C++/WinRT, which to this day after 4 years in development, still expects developers to manually edit IDL files and the generated code without any kind of Visual Studio tooling support.
Now they have WinUI 3.0 with 1700+ issues on Github, with Project Reunion just hitting 0.8, with the very long term roadmap of unifying everything, assuming it doesn't get canned as well.
So most of us that believed on the ideas behind WinRT just gave up, and went back to classical Forms/WPF/Win32.
