I do agree that Google creates some projects which aren't the greatest but there is a major difference between Flutter and some other random project.
As I said, Flutter is going to be the official way of building apps when Fuchsia os comes out.
I also have worked with Flutter & React Native, And I do see the difference. I find the need to import a third party library for navigation, icons, types of buttons silly. Another reason, all those libraries are backed by third parties, not Facebook. If they stop supporting it.... you get my point.
Where as with Flutter you don't need to go scrounging the internet for simple libraries that should come comes second nature... like navigation.
Dart also compiles into native code. No dealing with any crazy JavaScript layer.
Also, the reason why I believe Google is one of the best companies on Earth, is because they do their crazy projects, and aren't afraid to fail, and is willing to let us developers and hobbyist try it out. But I believe that You and I can be sure that Flutter isn't going anywhere any time soon.
One look at the documentation should tell you that.