Relatable. Presumably what takes it to click is the original knowledge, as presented in the book, plus the experience one happens to accumulate over time, even unrelated to the original knowledge. In other words, the author expected for the reader to click based on the pure knowledge alone, which has since been proven inadequate. So, in a sense, it's the author's fault.
PS: electrical engineering has one of the most reader-hostile presentations, so all authors should be tried for crimes against humanity /s