> I was in DevDiv during his great WinRT push and the overall feeling I remember was that the guys in Windows had zero clue as to what the devs actually wanted, but were hell bent on scorching all the ground that wasn't theirs. My team actually did some prototyping for Python/WinRT support, and we had it working to the point of the visual WPF designer in Visual Studio even. Unlike JS, it was full fledged - you could use anything in WinRT same as C#, extend classes etc, while JS limited you to a "consumer" surface of the API. That prototype was killed because Windows (i.e. at the time = Sinofsky) said they didn't think developers cared about anything but JS so they didn't need another high level language.

I think the real mistake there was not so much that a particular projection of the Windows Runtime was stopped, but the more general idea that developers should be forced to consume what became known as the Universal Windows Platform or author custom WinRT components through only Microsoft-made WinRT projections.

In the name of winning over new or inexperienced Windows developers with "simpler, safer" projections, we in the Windows division almost completely failed for about 5 years to document or even explicitly say that WinRT was essentially just "COM: The Good Parts, Version 2012". (Martyn Lovell's Build talks on the origin of WinRT were a notable exception to this.) This discouraged people from using their existing COM skills to develop Metro-style/UWP apps or to gradually adopt features from UWP APIs that were accessible to them in their existing desktop apps. Other people have written that "WinRT=COM" thinking is actually a bad idea because it forces people to deal with COM and its more annoying ideas (separate IDL etc.); I disagree because we should have reached out to people who live in COM world to get a ready developer base.

That mistake was a key part of the still larger mistake you touched on of trying to make the UWP and desktop worlds 2 completely different developer platforms that happen to co-exist on the same desktop edition of the Windows OS. That was the key "we didn't listen to developers" mistake that set up UWP for its market failure. Another example: Even today, you can't adopt the battery-friendly UWP app lifecycle using Windows App SDK, which is supposed to be the UWP successor for desktop app developers. So much for WinAppSDK (or indeed UWP/Metro-style apps in Win8) enabling a true no-compromise user experience.

It took real tours-de-force like Kenny Kerr building C++/WinRT and blogging about it, Raymond Chen blogging about using WinRT APIs through the unprojected "ABI" interfaces, or the VideoLAN organization building a Win8/Win10 UWP version of VLC in C, to get the word out that the UWP world wasn't some alien thing with dark magic that only Microsoft wizards had full access to. And it doesn't help that the wizards really do have a few special powers that they jealously guard even now.