I agree that it may be overkill for such a simple function, but the author (at least the original author, Brandon Rhodes) is drawing an analogy to more complex applications.
He uses such a simple example so that his idea that applies to much larger, more complex codebases can expressed in a presentation/article, not to argue that all such simple functions need this level of decoupling.
People pick catchy titles; it's a key part of getting noticed these days.