Essentially, I agree with everything you said -- the core of my complaints about this book excerpt is that it seemed to confuse the areas of responsibility for caches (and their structures) and efficient storage data structures.

I do think that analogies should be less, for want of a better term, leaky than those presented in the article: if they hadn't dragged CS topics into the discussion, I would've upvoted a reasonable productivity article and left it at that.