One of the nice things about Go is that the io.Reader and io.Writer interface being written into the base libraries means a lot of code gets this right, and only expects a stream rather than "a socket".
The takeaway here is not that Go is awesome; the takeaway is a lesson on the importance of getting a very early release of a language and its stdlib correct. The vast majority of modern languages today could trivially-to-easily do the same thing, but they don't in the standard lib, so the first couple of libraries end up string based, so the next libraries that build on those end up based on strings, and before you know it, in practice hardly anything in the ecosystem is implemented this way, even though in theory nothing stops it from happening. (Then around year 3 or 4, a big library gets built that does this correctly, but it's too late to retrofit the standard library and it only ever gets to about 10% penetration after a lot of reimplementation work.)
The takeaway here is not that Go is awesome; the takeaway is a lesson on the importance of getting a very early release of a language and its stdlib correct. The vast majority of modern languages today could trivially-to-easily do the same thing, but they don't in the standard lib, so the first couple of libraries end up string based, so the next libraries that build on those end up based on strings, and before you know it, in practice hardly anything in the ecosystem is implemented this way, even though in theory nothing stops it from happening. (Then around year 3 or 4, a big library gets built that does this correctly, but it's too late to retrofit the standard library and it only ever gets to about 10% penetration after a lot of reimplementation work.)