As much as most don’t like Facebook, I honestly don’t see why Facebook is at fault here. They’ve got a platform where advertisers come on, say “I want to sell ads to people Ages X-Y , Gender A, in Geography I, J and K”, and they serve ads accordingly. What are they supposed to do? Tell the advertisers “No no no, you need to also pay for ads on these other demographics that you explicitly excluded”? The plaintiff should be suing advertisers, not Facebook, for intentionally not targeting them.