But the distribution of profit is completely different in those two cases, and that's legally relevant.
When you go on the dark web and buy something illegal, the money goes to the seller, whereas presumably nobody is directly profiting from the torrents.
Are you being serious here? How do you think courts deal with these issues every day?
Common sense. A pirate bay clone would still be knowingly and intentionally distributing links to infringing material, whether or not doing so without a financial incentive is illegal depends on the jurisdiction.
If only determining that something is infringing were that easy. Given that everything fixed in a tangible form is copyrighted, and then copyright lasts until after the author has died, I have to know who fixed the material, when, and if they're still alive. It's an impossible situation, and you're glossing over it like it's easy and automatic.
And what makes it different from the hypothetical drug blog? I'm not saying it's innocent, I'm saying there's some weird mismatch here where you can't go with a mile of a copyright infringement but you can get pretty close to normal crimes as long as you don't touch anything or join a conspiracy.
When you go on the dark web and buy something illegal, the money goes to the seller, whereas presumably nobody is directly profiting from the torrents.