Dart is also Google sponsored and no one uses it despite the fact that it's actually a pretty great general purpose language. People use go because it's productive and had a PHENOMENAL standard library for networking.
Citing an example that had support from Google and failed does not refute the claim that Go would have failed if not for Google's support.
Whereas there are a few production examples of Go at Google.
In this case a company team was allowed to use a competing language instead of the one designed in-house for the same purpose.