Ask HN: Why can I send people on FB messages when we aren't friends?

Hi,

I'm just wondering why can anybody send messages on FB to others when they are not friends, and when their privacy settings is that only friends can message them.

All I had to do to send a message to a person who wasn't a friend is click on "new message", a box popped up, in the field "to:" I copied the username from the url on that person profile, and then append "@facebook.com" and the message was sent, when I checked my messages page, a message was sent to that person and his picture and name on FB were shown.

Is it intended to be like this?