Very true. We just developed a brand new LOB desktop app and settled on sticking with WPF. WinUI has been dead for years imo.
On a side note, I still love WPF after working in it for 10 years. Maybe it's just familiarity, and it's a little verbose at times, but man it's a great framework when you know that you're doing.
We also settled on WPF for a new LOB Desktop application, this validates the decision. If you combine WPF with the CommunityToolkit MVVM, it’s a very nice framework to develop with.
DevExpress supported WinUI for a little while but decided to abandon support.
One of the biggest problems with WinUI compared to WPF is that DependencyProroperty is implemented as native code, so for .NET developers, there is a huge performance penalty getting or setting any property on control.
WinForms and WPF are currently the only viable frameworks for Line of Business application. I have yet to see a WinUI3 application in the wild.