So I am relatively naive when it comes to declarative programming in general and have not yet read this paper (I will after commenting here), but that said...

Don't you have to (at the very least) tell the compiler how to do things? To reuse the example from the article: when you tell your friend to get you a beer, at some point your friend has learned HOW to get you a beer. Similarly the compiler will need to know HOW to do things that you declare. Sure it will be great when we can just tell the compiler that we need this list sorted in reverse alphabetical order but at some point someone is going to have to program the sorting algorithm on the back end.

Am I way off or are we just talking about a hypothetical future when compilers are (even more) black boxed and we don't have to think about them anymore?