Sure, I understand it's for mutual "protection" and so on.
But face it, in this electronic age, almost no information remains secure.
Elliot Spitzer got caught. Heidi Fleiss released her whole rolodex.
Giving out your name and address and business address and phones and so on makes you vulnerable to all sorts of trouble, from blackmail (the least likely) to simply exposure and embarrassment (and divorce!) to outright identity theft.
I can't be the only one nervous about this, can I?