Also I'm more of a custom approach person which makes me very productive with Go. It's allows me to have laser focus on my needs instead of hooking up and reading docs and every little integration feature the framework has. And in result, I don't have dependency on a monolithic framework which could very well break everything in it's next release.
And finally, Go will build to binary for any-platform. So I can pre-build for the ARM processors, or Linux, or whatever else on Windows and just ship the binaries for server updates instead of managing make scripts and dependency resolution and blah blah blah. And if I wanted to I could sell the API "program" and sleep a little better about the IP contained in it (yes I know de-compilers exist). I could do this with C++ as well, but that's a whole 'nother ball game when it comes to tracking down memory leaks and segfaults.
Furthermore, Go emphasizes "doing it your own way". There are no big web frameworks in Go, you just pull in some small and rather orthogonal libraries and make up your own abstractions to tie them together as you build your application. The end result is something that's highly optimized for your personal needs, but it requires a certain way of thinking and working that's not for everyone (and not always desirable). Some people do better when given more freedom; those should prefer Go etc. Some people do better when working within a well-known set of rules; those should prefer Rails etc.
Regarding ORM, I use Gorp (https://github.com/go-gorp/gorp) for INSERT, UPDATE, DELETE and basic SELECTs (e.g `SELECT * FROM things WHERE id = $1`), but when doing complex reports, I write SQL by hand [1] because ORMs are usually too constrained. I always feel like I know more SQL than the people who designed the ORM.
[1] For example: https://github.com/sapcc/limes/blob/ab4245a8f195672b808f990f...
Just that you might need a library for routing like https://github.com/julienschmidt/httprouter
Also Go is one of the few (if not only?) languages with HTTP/2 built in to the standard library. Not to mention the gRPC over TLS that comes stock as well.