WPF started XAML, then came Silverlight, WinRT and UWP. They are superficially similar but under the hood the code is quite different and each has its own set of weird limitations so you can't just reuse code. Also, in the case of WinRT and I think also UWP the new framework had less features than its predecessor so in a sense it was worse and less powerful which is not a good way to convince people to port their code.

When WPF came out there were quite a few very cool open source projects that built on top of it because it's really easy to extend WPF and build components for it. But then every two or three years MS announced a new framework so most of these efforts died out. When you look at commercial third party suppliers like Developer Express they have the same component in three or four flavors. this must be a huge and expensive effort to maintain.