They're not about designing distributed software systems... they're a complete design language for the proper design of a city, from the grossest elements to the most granular. You can flip to a random page and understand what makes a front yard really fulfill its purpose, or you can flip to a different page and learn why some public plazas just don't get used, while others flourish.
It's a template system for designing a room, a house, a neighborhood, a city, etc.
Makes you think about what a component is, what makes it "good" or "bad" at what it's supposed to do, and what makes it harmoniously integrate with other components.