> Meanwhile I can just add 3 annotations in Spring/RoR/Django and have solved the problem in a way that a competent new hire will instantly be familiar with.

If you're building apps that are understandable to new hires, you're right: it's all just boilerplate CRUD.

> Python and ruby backends are all over the web and they perform completely fine

Python certainly doesn't. I've got one inherited service running in Python/Django, and it quickly grows to 1GB per worker, and even then manages to be so slow larger queries time out. I've written two new services in go, they get more traffic, and they run in 20-60MB, with peaks over 200MB. I can run both services and multiple development versions on a 2 CPU, 4GB machine with room to spare.

> in another language you would have just added an annotation and 2 lines and called it a day

I sincerely doubt that. The only boilerplate in go is the error handling. The rest is comparable to Java/C#.