> You say that so definitively. Have you worked on a product with millions of new users a week? It's an extremely hard, constantly shifting problem.

Facebook has hundreds of engineers and enough data to do match patterns against. Facebook can largely identify who's who.

> Facebook's entire business relies on user and advertise trust. Why would they sacrifice that for some short term growth that would inevitably kill the business by eroding trust?

Yes, the infamous "they trust me, dumb fucks"?