Well, the truth is that I really like Kotlin. I find it very concise, powerful and balanced. But the article isn't about just "why Dart is not Kotlin". Most of the points I've mentioned can be found in other languages.

At the same time, Kotlin and Dart share pretty much the same use cases. Both companies creating the languages claim them to be good at back-end, front-end, mobile, desktop development; but Kotlin looks more powerful, safe and mature for me to better fit that role.

Flutter, on the other hand, is really great framework, so I continue to use it for cross-platform development – despite Dart, not because of Dart, unfortunately.