Why? Well, Agile is about people, trust, a few simple rules, but most of all everyone pitching in to get things done - mob like? I think so, well maybe ;)
Below is a link to a presentation I did in my previous role a couple of years ago - it tries to show some relationship between the roles, processes and artefacts of scrum and the mob - along with some very dodgy Italian pronunciations :)
Within an Agile project and within your typical mob, there are some roles that need to be filled which have special jobs; There are those that define the direction, there are those that make sure that there are no road blocks, and there are those that listen, report and out in the firing line.
I know its a bit silly, but in thinking about it, it made me realize how important the people are in Scrum, not just the artefacts and the processes. A project is run by people, for people. A mob is run by gangsters for gangsters.