Exposition, the explanation of complex ideas, benefits from carefully planned serial order. The ideas unfold as an argument or story. Damage is done by skipping around. In short, when one is solving a problem or exploring, hypertext may well be superior to ordinary text. But in learning something new, particular when there is a lot to learn, ordinary prose will probably be better most of the time.
Ordinary prose provides a preplanned train of thought, and the reader can ride along.
This leads to certain logical conclusions, in answer to the question posed at the top of this document. The knowledge of an expert consists of an incredibly complex network of interconnected concepts, built up by repeated encounters with informative situations in the real world. Hypertext is not a bad way to encourage such exploration, and it can also be used to show the result.