At which point you'll very likely learn that a lot of widget-related websites use ad networks because it saves the 2-3 administrators involved a lot of time and

At which point you'll very likely learn that a lot of widget-related websites use ad networks because it saves the 2-3 administrators involved a lot of time and energy. It's definitely possible for small websites to do ads directly, but it's a lot of work. Often more than is justified for a few thousand dollars a year in ads.