No you're absolutely correct. If someone takes your photo (I read about this for a childrens entertainer and someone duped her account) facebook will disable the persons account and likely depending on the situation may take extra steps (I believe in the case I'm thinking of, Facebook gave a list of the IP's and times the user had accessed the duplicate account from to the police in case they believed it was potentially criminal due to the nature of the womans job and the likely hood of the dupe being made by a pedophile).

Facebooks ToS explicitly state that they respect the IP rights of others and that they will remove any infringing content, or for repeat offenders their account will permanently be suspended (presumably their email will be banned too). It also says they do everything in accordance with the DMCA. The one thing people don't understand about the DMCA is that whilst it might be evil, it also protects individuals as much as companies because every single photo, sentence or anything you or I make or write are immediately copy protected in all western countries.