Now that we have a wildly popular augmented reality game, the risks posed by augmented reality are starting to make themselves known. People are wandering into places they shouldn't, and some of them are getting hurt or worse. While the game may augment reality, either the tiny screen is acting as blinders to everything off the screen or virtual reality games (such as 1st person shooters) have trained us to ignore threats when gaming because we can always start over.
Either way, having someone around who isn't playing when you are has the benefit that they aren't in that world and they can warn you or pull you back from walking into a dangerous situation.