Security reasons. It can be used to confirm whether or not a certain file exists on another PC on the network by observing where it&#x27;s synced to&#x2F;from.<p>That said, there&#x27;s nothing novel here. People have been doing this for decades, and extensions to the bittorrent protocol use it all the time to prioritize LAN seeds over internet seeds. In fact, I believe there was talk a while back about optimizing BT to prioritize peers and seeds on the same subnet&#x2F;ISP as a way of mitigating ISP bandwidth concerns and whatnot.