Agreed, but a common extension does not mean it is required, nor that it should be demanded that an example of making a REST service needs to show how to do it.

The example is simply the beginning. It can be extended as needed depending on your use case. This is how most things Golang work. You start with the basics and add what you need on a case by case basis.

If you want something with every bell and whistle out of the box, Golang is going to be a disappointment generally as that is not the Golang mentality.

There are of course sufficient frameworks in Golang these days to provide such things though. Hence the article clearly says "standard library" to indicate that it isn't the last word on how to setup a REST service in Go.