I can answer this one. I could explain to you every aspect of go's net/http package and database/sql package. The interface is compact, and even the source is very legible and easy to digest. You don't need all the extra bullshit to build API and run CRUD operations. I am a former RoR developer. I have lost no speed in just using simple tools and simple packages.
Also, I can have a junior or associate developer from any background get up to speed in a matter of days. Where as when I was at the Rails shop, you specifically had to hire a "rails guy/gal" and even then still took them days to get started.
(Don't mean for this to be a "go is great" rant, I am sure there are equally simple tools out there - Dropwizard is another one that comes to mind -- just a bunch of jars glued together)