They claim to have an "industry-leading security profile" and yet they allowed user generated content to be hosted under their primary domain. At least this was an inexpensive way to learn that lesson.
It's like negative SEO for social media sites. Associate a service/company you dislike with spam and offensive content, flood social media services with it and get them wiped out immediately afterwards.
It's a trick that'd probably work just as well on Twitter and Reddit than it would Facebook.
Indeed, this trick should work on any social network, that's scary! Although it seems facebook is now doing a good job to quickly review again and unban domains when the offending content is removed.