From the article it seems they were needlessly using classes and doing funky stuff with Python everywhere. It speaks more about the quality of team than the move to Go.

I've used both and maintaining legacy Go code is still quite a nightmare with the bazillion ways people can fuck up dependencies, error handling, and non existent types. Python is ok in comparison, not good, just ok. If I wanted a dynamic language that offers speed I would have just stuck with Common Lisp tbh.