Dart scores highly for us on the following primary criteria:

One of Flutter’s main value propositions is that it
saves engineering resources by letting developers
create apps for both iOS and Android with the same codebase.
Using a highly productive language accelerates
developers further and makes Flutter more attractive.
This was very important to both our framework team as
well as our developers. The majority of Flutter
is built in the same language we give to our users,
so we need to stay productive at 100k’s lines of code,
without sacrificing approachability or
readability of the framework and widgets for our developers.