They needed to work with a language team that's willing to modify the language to meet their requirements. Dart needed a killer app and was willing to work with them. The rest is history.

JavaScript was invented for similar reasons (though by one person).

I've been working with it for about 6 months, and TS a couple years before that. Dart is missing some things, but it's alright. The standard lib is great.

Why does everything have to be in JS? I'm all for making JS better for the environments where you have no choice but honestly even with TypeScript it's still a pretty deeply flawed language.

Any decent dev should be able to get up to speed in Dart in a week.

I've worked with a few interns that were interviewed and tasked with small scripts and libs to be developed in Dart. Most of the "got" the language in a few minutes, and were productive in a few hours. (Disclaimer: they were all using the IntelliJ community version with the Dart plugin, but hey, tooling is there for a reason).

I don't like Dart much to be honest as well, I've tried used it for about a week to try Flutter and the experience has been pretty bad. It feels kind of Java-like to me, which is really not a positive thing.