Not quite true. Facebook does behind the scenes correlation of phone numbers to emails to user accounts (and anything inbetween), even if you didn't provide all of the information.
1) You have a Facebook account and tie it to your email.
2) I have a contact in my phone with your name, your email, and two phone numbers.
3) I sync my contacts to Facebook
4) Facebook now associates all of that data with you. Doesn't matter if you ever made it public, supplied it to Facebook, or if that user is even your friend. They even keep this information for people who haven't signed up, and will instantly associate it once you do sign up. That's how you'll see a lot of people you actually know instantly pop-up in "People you may know".
Look for some old threads under 'latest news' from last June about this. I actually found a hole which would allow you to export arbitrary user's contact details from Facebook as long as you had at least one phone number or one email of theirs. And surprise - everyone with Facebook has an @facebook.com email address. This hole was covered in major media, and I was given $12k USD hush-money (err, "bounty") for reporting it to them first.