Not a great justification, but it made a bit more sense then.
The solution is to use user interface toolkits that are available on each platform. For example, wxWidgets or Qt or appropriate bindings to them if you can't be bothered to write UI code for each platform you're targeting.
Why not? Microsoft released IE for win16, win32, wince, macos system 7 through 9, macos X, Solaris, HP-UX. If it ran on all those platforms, Microsoft probably could have supported it on any platform that had the capability of running graphical web browsers.
I don't see how reusing web code is an advantage. Web code is for the web. We are talking about a native platform (Windows 11) which has a mature API platform stretching back decades. Why would you need to make it "web"?
"Now you can have the cross-platform compatibility of a single-page application just by bundling Chrome."