Well, to look at it from another point of view, I'm pretty sure this has to do with COPA regulations, which try to shield minors from things they should not be able to see -
US Supreme Court and COPA Laws"COPA defined the posting of material that is "harmful to minors" on the Internet for commercial purposes as a criminal offense. But the Act also provided that website operators and other content providers could defend against a prosecution under the Act by showing that children's access to harmful content was restricted by requiring the use of a credit card, a debit account, an "adult access code" or "adult personal identification number," a "digital certificate that verifies age," or "any other reasonable measures that are feasible under available technology.""
So they were trying to do something which had a legal meaning.