I did find that odd. Whitespace helps you get away from "a wall of dense text." I'm not clear on how mandatory whitespace could exacerbate the "wall of dense text" problem.
Does the author want to skip the indentation some of the time? I can think of a few marginal cases where that would be preferable. But in the vast majority of cases, you should indent any nested structure that has its own line(s). Indentation is essential for readability.