No. As someone whose PhD touched this: it is actually ok because it stabilises towards using the most available paths. As someone who set this up at an ISP: y

No. As someone whose PhD touched this: it is actually ok because it stabilises towards using the most available paths. As someone who set this up at an ISP: you can QoS the hell out of P2P and keep everyone happy. That's unless you tried blocking it and now find yourself in a stupid arms war, against folks with more free time than yourself.