Not really. In a p2p scenario with n participants, every participant needs to send (n - 1) copies of the packet. In a centralised scenario, each participant sends just one copy of the packet, and the server duplicates it (n - 1) times. Whether this is wasteful depends on where the server is located. If the server is close to the receivers, it is a net gain. If the server is in the US while all of the participants are in Europe, it's a terrible waste, since all of the packets need to cross the Atlantic. Server federation solves the issue: you put one server in the US, one in Europe, and each packet crosses the Atlantic exactly once.