I got exactly the same impression. The cul-de-sac per se isn't even addressed. Taking it as symbolic, the article's main argument for grid layouts seems to be l

I got exactly the same impression. The cul-de-sac per se isn't even addressed. Taking it as symbolic, the article's main argument for grid layouts seems to be little more than "everyone was doing it 100 years ago, and we found a handful of favorable correlations, so they must have been on to something".