>And yet Go pretty much ate the lunch of C# and Java when it comes to backends and devops, despite the fact that both had a decade of head start and generics and large dev teams behind them.

This is simply not true. Go is nowhere near that even when only new Greenfield projects are considered. I see many of the start-ups using it but most new projects are still in Java or c#. But go has captured the Dev ops tools area quite a bit.