Sane by your definition is not the same as my definition then. A community can't grow if people aren't a part of it. Using Dart is one of the best decisions I have made in my life.
The decision to use Dart for this project seems to me like an attempt to find a lifeline for it. That's fair enough, but it could ultimately be a highly limiting factor and the reason it doesn't go anywhere. That would be a shame as cross-platform frameworks need to keep evolving to be more useable and performant.