It’s obvious that a city of millions of people cannot be served by one hairdresser. And it’s not only about the number of potential customers. Different people have different needs. Some want to just shorten the hair, while others look for a fancy hairstyle. From time to time Adam has his hair cut. But he doesn’t go to the same place Brian does. In the end it’s all about having your hair cut, but they expect it to be done in very different ways. And it’s totally fine to have different ways of getting your hair done, so is to have few libraries handling HTTP requests.
After living in that big city for a while, both Adam and Brian know which districts should be avoided. They know the city is not perfect, but they stay there because of all those possibilities they would never have in a small town. They create the city.