To be fair. Creating a good cross UI framework is hard. Winforms wouldn’t cross over to OS X / linux. WPF was too heavily tied to Windows. Silver light was a compeditor to flash and both of those died. Now we are up to Maui and Avalion? Blazor is more silverlight replacement imo.
Also, Winforms and WPF were designed before Microsoft embraced Linux and started making .NET truly cross-platform. Starting over with a new cross-platform UI framework sounds like a reasonable thing to do.