The same argument can be extended to the Internet as a whole.
Agreed. Your point?
As such it does not hold a an effective criticism of P2P sharing systems.
As such? Were you planning on providing an argument? Or are you simply going to define theft out of existence for certain realms?
The fact that a large network of computers is involved in a theft does not mean a theft did not occur. It just means it is more difficult to place blame. But that is what a court of law is for - to gather all the facts of the situation and at determine who is to blame, to what extent, etc. The same goes for, say, a mob stampede/riot.