The first time I read this I saw this as just a means of a Certificate of Authenticity, e.g. Never did I think of it as a means of privacy intrusion.
Subsequently, Bro & Co. will be able to pinpoint, if at all, who's selling theirs for an extreme profit, or abuse their caps in any other way, and possibly ban/warn them from/of future sales, should they wish to do so. I guess the only way they can do that is become notified of a marked-up sale, see some pics of the certificate, and see who originally owned that number.