I find part of the argument deeply flawed... In particular:
> Dart is not a widespread language compared to ... Kotlin, Swift
The main reason Kotlin and Swift are widespread is because they are platform languages themselves. Part of considering a cross-platform language is expressly to avoid/reduce the tether of platform languages.
While it seems that I have to remove several Flutter articles a week, I can see the appeal. I also see the appeal for React Native as well as the work on Xamarin Forms, and the MAUI support coming in .Net 6 (though lack of Linux targets in the near term is disappointing there).