This is a pretty arbitrary benchmark. I would guess, again, that 95% of programmers have never and will never need to create a tree map. Repeat for numerous collections and APIs that are totally irrelevant to most programmers' actual experience of programming.

Go is optimized for use, not computer science edge cases. And as a result it is widely used, and some of the most complicated and widely-used open-source projects out there are built in it, even before it had generics. For example, Kubernetes.

This is because of Go's simplicity, not in spite of it.