I could be wrong but I don't think he was saying "point-to-point communication" in the technical aspect of the term (i.e. peer-to-peer). Rather, just making the point that they're not storing tons of data on their server that has to be polled on demand by an unknown amount of clients forever. Even if there's a server between the users, once they receive a message and pass it onto whoever necessary, their job is done and they don't need to worry about that data any more.