I'm surprised that anyone could have that response after reading the article. It is very clearly talking about space wasted primarily in hallways and in the restrictions that requiring two stairways puts on floorplans.
Yep, that's what I'm talking about. Those things are important negative space. What would you get, one more apartment per floor? Let's not crawl over each other like ants.
You could get larger units or cheaper units since everyone is paying for that floor space which is potentially not required.