It's not about having people with the same name, or identifying a person uniquely for the purposes of a program. It's about people changing their legal birth name in the future to a unique choice that means something to them so that they can have a single identity across all social networks or communities. They will want to do this because social networks and communities will be so ingrained into every day life, so much so that their online identity will have more meaning to that person than their legal birth name.