But if they break through the encryption, there should be no legal penalties for doing so. When it comes to Napster, there's a big grey area and they are on the shadier side of it. Or have millions of people trading thusly with millions of non-friends. Even if Napster is ultimately shut down, many people are designing file-sharing programs that would be much harder to pin liability on, and with no center that can be sued or squelched. But merely making it hard to catch or stop people who use it complicates, rather than solves, the problem.
DOES have real and substantial uses for all sorts of legitimate things.
The Web is such a technology, so is the Internet. So are xerox machines and personal computers. Napster and its ilk are the baby-steps of a new leap in this capability. It would be like banning pencils because bookies use them to record illegal bets. That's how to make a copyright law that clearly and accurately draws a line between what is socially acceptable and what is legally punishable.