Also, IMO just the presence of a clear TOS is a deterrent for all but the dedicated abusers who don't care about prosecution.
Another example is if you are a web service that doesn't comply with DMCA provisions, you may be liable for your users actions.
What I am trying to say is that a TOS does not indemnify as a matter of law. The question of fact for each specific issue will be sent to the jury who will decide your fate.
Whether a TOS creates a contract could also be decided by the jury. They aren't contracts 100% of the time.
Of course cases with citizens of different nationality are different and much more difficult to work with, even with a paper contract. Both governments must be willing to hold their citizen up to the agreement in the contract. If I have a contract (printed, signed, and notarized) between myself and the deposed king of Nigeria, it would be hard for me to take the ex-king to court.