It's hard to describe how uselessly restrictive the UWP model was when they originally introduced it as "Metro-style apps" in Windows 8. Among the things it officially did not support included:

- Multiple monitors - Non-full screen views - Sideloading outside of the Store - Offline installation - Explicit threads - thread pool only - Aligned memory allocation - malloc only - Any C++ compiler other than MSVC - Support for any version of Windows other than Windows 8 - Running apps as administrator - Running more than one instance of an app at a time - Runtime shader compilation

If any ONE of these things was a blocker, you could not write a Metro style app. And yet Microsoft pushed this extremely hard -- including almost completely ending any maintenance of Win32 APIs. And despite the many relaxations and extensions, UWP is still largely useless today, and now even itself seems to be going into maintenance mode. All of which has done a lot of damage to the state of Windows desktop platform development.

As an example of how bizarre UWP is, for some reason every time they published a list of new APIs added to it, they converted the list of API identifiers to lowercase in the documentation:

https://learn.microsoft.com/en-us/windows/uwp/whats-new/wind...

It's relatively insignificant, but... why? Just one of many things that showed how immature UWP was.