[scythe]

Microsoft had an underlying operating system that they wanted to rewrite substantially in C# on the .NET VM. They had a decent motivation for not having a core piece of Windows dependent on a product from another vendor that was competing in some of the same markets as their core product.

Google by contrast isn't nearly as invested in Dart as Microsoft was (and still is) in C#/.NET. Perhaps a better objection is that they should have just used Go — or a Go-binary-compatible language built on some of the same toolchain. (See also: Vala and Guile still don't play nice together as well as they should for two languages from the same project.)