I agree. I think the quoted professor-authors' point in the quoted passages is to make a book like SICP, designed to teach deeply rooted computer science concepts more approachable to beginners without going to the extreme of "How to build a webapp in 12 days". I support the effort, as I think it's a bummer that the choice as a beginner is often between a too-difficult SICP and overly abstract and non-theory-based tutorials.