Google kept on building C++ services despite Go being available and fully backed by the company. Developers could have used Go if they wanted to, but they didn't.

There are obviously exceptions. There always are. But the reality is that Go was picked up by the Python crowd instead. Which was noted as being surprising at the time as it was assumed that Python users didn't need another Python. What was hard for the Googlers to fathom was that anyone would use Python in a performance-sensitive area to begin with.