The private tracker community have long figured this out. Put content behind invite-only user registration, and treeban users if they ever break the rules.
replies(1):
I do fear the actions of the current bot landscape is going to lead to almost everything going behind auth walls though, and perhaps even paid auth walls.
One of the practical problems I rather saw was bootstrapping: how to convince any website owner to use it, when very few people are on the system? Where should they find someone to get invites from?
As for tracking (auth walls), the website needs not know who you are. They just see random tokens with signatures and can verify the signature. If there's abuse, they send evidence to the tree system, where it could be handled similarly to HN: lots of flags from different systems will make an automated system kick in, but otherwise a person looks at the issue and decides whether to issue a warning or timeout. (Of course, the abuse reporting mechanism can also be abused so, again similar to HN, if you abuse the abuse mechanism then you don't count towards future reports.)
Ideally, we'd not need this and let real judges do the job of convicting people of abuse and computer fraud, but until such time, I'd rather use the internet anonymously with whatever setup I like than face blocks regularly while doing nothing wrong
I think a sort of pseudo-anonymous auth system with backed in invites and treebans that website owners could easily adopt is interesting though. I'm not sure it's a business - for adoption reasons it likely needs to be a protocol - but it's an interesting idea, if it doesn't just turn into a huge admin headache for publishers.