...some very dense cities don't have much in the way of very tall buildings. Paris often comes up in this regard, but a better example for the American context is probably Somerville, Massachusetts where I happen to be at this very moment.
Somerville, a highly urbanized "suburb" of Boston contains over 18,000 people per square mile making it somewhat denser than San Francisco. And yet it has few tall buildings and certainly no skyscrapers. The key to that happening is that it's very literally dense. The streets are narrow, there's very little parkland, there are few office buildings or hotels. And most of all, the dwellings themselves are small. It's no coincidence that this town is in the oldest-settled part of the United States. Over the years as America has gotten wealthier people have tended to live in larger and larger spaces, but Somerville is full old structures that fit two or three households into apartments that cost more than the average American dwelling but have less square footage than the average American dwelling.
Read the whole thing here, including a huge number of comments (probably 20 times as much text as Yglesias's story)