I agree with you, the point I was trying to convey is that Google isn't betting on Dart as a pioneering, untested technology as Rust is.
Flutter demonstrates Dart is a good choice; it gives you a successful declarative UI framework that effectively builds on Dart as a fairly straightforward upgrade of the most tried and true UI scripting language ever made: Javascript.
To answer the GP comment, betting the house on Dart for the UI doesn't seem like a strange or risky decision in that light.
That you like Dart and that it's a good fit for UI development doesn't make it less risky.
It still seems incongruous that widespread usage is portrayed as an important criterion for Fuschia PLs, but they bet big on Flutter which forces them to adopt Dart, a language which has very little uptake outside Flutter.
I'm not sure how you got "I like Dart" from my two comments. I'm clearly saying that Dart & Flutter are based on very popular and well tested concepts/structures, therefore it is not very risky. Dart & Flutter by themselves may not be very widespread, but it's very familiar and easy to adopt to anyone who has done declarative UI web development in Javascript or Javascript-like language, which are widespread.
Rust, on the other hand, is treading new ground with the unusual core concept of a borrow checker.
Flutter demonstrates Dart is a good choice; it gives you a successful declarative UI framework that effectively builds on Dart as a fairly straightforward upgrade of the most tried and true UI scripting language ever made: Javascript.
To answer the GP comment, betting the house on Dart for the UI doesn't seem like a strange or risky decision in that light.