My Day Job website with several 100,000s of users doesn't block TOR traffic - but it does red-flag any such users as suspects, with good reason. All of the latest attempts at creating users with identity-fraud have come from a TOR source.
Then we resort to software tactics to make the connection and session look bad. Better to make the suspect users think it's just a crap website than letting them realise they've been rumbled.
Biting the hand that feeds IT
