This is not true.

Facebook builds profiles about millions of people who have never had a Facebook account. For example, people who happened to be in the background of a photograph taken by a stranger. Another example: people who installed an app on their phone without knowing that it included a Facebook SDK that was tracking them.

This is nothing new. It's been discussed in public, and even before the U.S. congress.

Personally, I'd love to opt out of Facebook. But I can't. Because I can't log in to my Facebook account, and Facebook ignores my requests for access. I even did the "send in a picture of your government ID" route, and nothing happened. So please inform me how I can opt out of Facebook's data gathering.