This extends to many areas. Gun manufacturers aren't liable when someone goes on a shooting spree with a gun, for example.

I feel like this is a slippery slope. Facebook lets anyone advertise anything, and gives everyone the same targeting tools. If you use them illegally, that should be on you, not on Facebook. Just like how you can use a screwdriver to screw in screws, or to go around stabbing people with it. The difference is that screwdrivers are a well-understood tool, whereas ad targeting tools are new and scary.

If you want to make advertising illegal, I'm fine with that, but good luck.