What a bizarre misquote... busy beaver programs are a specific type of algorithm, in the sense that you want to extract the most possible output, barring infinitely generating functions. It makes a lot of sense that the programs be as complicated as you possibly can make them, from the conceptual level to the explicit coding, because the problem space is densely complex and most of the simple stuff has been iterated over.

It's a statement about number theory, not general software design best practice.