How many real life cases has it been impossible to ascertain the identity of trouble-causing site's owner, anyway? Everyone knows who is behind Wikileaks, for example. Anyone else wanting to do disagreeable things is far more likely to do it on the many existing platforms instead of hatching the complex fake-identiy/credit-card scheme to purchase a TLD that can't be easily tracked to him/her.
To become effective participnts in politica, the tech community activists have to tilt less at thinly supported grand conspiracies and focus on the more mundane workings of the sausage factory that produces our laws and regulations.
EDIT: I realize I've set up a straw,an, and in fact, there are many dissidents who'd like to have less requirements in registering a domain name...but why they would go that route rather than creating fake accounts on well-used services...in any case, Joel currently has the benefit of the doubt in arguing that the OP is factually wrong
Between pre-paid credit cards, non-verification of whois records and corporate registrations there are too many ways to avoid disclosing your identity.
(Currently, from memory, the only verification most registrars do is make you is enter a real credit card number even if you aren't paying with that. Pre-paid credit cards remove any identifying information from that.)
I'm not sure why this is even relevant anyway - the real problem with enforcing IP rules isn't identifying the person - it's jurisdiction. If a site is hosted outside the US and the domain is registered outside the US, and the country where it is hosted and registered doesn't respect US IP laws then there currently is very little anyone in the US can do about it (easily anyway).