Dart is an extremely limited language compared to TypeScript (it doesn't even have sum types), and has access to a much smaller ecosystem. Its runtime isn't muc

Dart is an extremely limited language compared to TypeScript (it doesn't even have sum types), and has access to a much smaller ecosystem. Its runtime isn't much better either, like for example Go's or Haskell's is. Deno has a partial implementation of Node's API, and even without it it's still the same underlying runtime concepts, so porting is easier than porting to another language like Dart.