Kinsella even spoke of this in his piece.
Imagine you give me that pencil, tell me that I can’t use it to write on white paper. I then break the contract and write on 50 pieces of white paper, sending 49 to friends and holding on to the one piece of paper. Kinsella made the point that, sure, you can hold the original copyright violator, me, accountable in a practical manner, but how are you going to pursue the 49 other fraudulent pieces of paper?
In a modern computer-affluent society, the practical application of enforcement becomes even more unlikely, because you’re not just looking at a determinable number of copies anymore, you’re now looking at an indefinite number of copies on the computers of an indefinite number of people.
Let me ask you this: How many people have pirated the computer game Fallout 3? You could look at the number of seeds for a torrent of the game, you could even potentially determine the likely downloaders from an IRC channel. Hell, you could search for an MD5 checksum on all the computers in the world if you had the right tools and everyone in the world somehow agreed to trusted computing. But the fact of the matter is, one individual can change a single bit and keep the entirety of the “practical theft” outside your knowledge even in such a draconian society. And I haven’t even covered the people who mod their Xboxes to pirate the console version!
Making this example more relevant, go back to the pencil. Imagine I died of natural causes. You don’t know if there are 4, 49, or 499 pieces of white paper I’ve written on. What do you tell the person who sold me the pencil?
If you’re an enforcer of IP, there will come a point where you tell the copyright holder “that’s all I can do.” While it may seem like you’ve gotten some vindication going after the original contract violator, there’s a point where you will come to realize that IP isn’t scarce, and thus cannot be property.
This is a debate that probably harkens back to the first cave paintings depicting how to take down an antelope while putting one’s self in the least harm and one clan using the knowledge gained from such a painting to outsurvive the rival clan, of which the original painter was a member. The clan that won wasn’t necessarily the brightest, but it most certainly was the better at adopting the advice of the painting. Evolution won.
Arguments since then in favor of IP have merely been from clans trying to prevent other clans from obtaining the same knowledge. This is protectionism, racketeering, and other vile things that we only associate with a statist government. To see an anarchist propose that we should have enforcement of intellectual property is quite ridiculous.