The point of the text is, that you have to define where to put the complexity:
If you are lucky, it lives in well-defined places.
With nowhere to go, it has to roam everywhere in your system, both in your code and in people's heads.
When defining the abstraction you focus on the practical use-cases so that it is as simple as possible but not simpler. The main task here is to find the right focus. In doubt, it might be better to use multiple different abstractions (e.g. if there are two distinct use-cases).
The goal is to find a construct where everything looks simple from the outside because the complexity is hidden by the abstraction.