[kbuck]

FreeNode's use is a bit more extensive than just requiring an email address - you have to create the account from a non-Tor IP, so if you do something bad and get banned, they ban the account (thus preventing further access from you via Tor) and then also have the option of banning the IP that registered the account (preventing it from registering further accounts that will be abused via Tor). If they really want to, they can also ban the email address, but in practice this really isn't worthwhile as it's so easy to get a different one.