Providing the tools to specifically do terrible things makes you liable.
This comes up rather often but the "disruptor economy" style business that try and replace existing things that are burdened by regulations and other boring things with shiny new things with Vue, rounded corners, blinking lights and a lack of those regulations are, in fact, totally responsible for their failure to adhere to those regulations.
I feel like D&D and friends are ultimately partially to blame here, and their long (and wonderful, I'm not knocking table top RPGs) history of encouraging pedantic rules lawyering. The US legal code isn't like a tabletop RPG where if nothing specifically says your Thri-Kreen can't quadra-wield bastard swords with monkey grip then go ahead - when laws fail to specifically address situations then the courts are present to try and sanely interpret the intent of the original law and apply it to the new situation.
That's sort of like how murder is illegal, instead of it being illegal to hit someone on the head with a garbage can, hit someone on the head with a tire iron, hit someone on the head with a crow bar... "Murder" isn't an action you can take without a lot of abstract assumptions.
So perhaps Facebook is like a hardware store that sells the...
Burgler Bundle - a complete set of a ski-mask, crow bar, knife and lockpick set
(do note "Burgler Bundles" are not intended for burglery, theft, larceny
or other crimes, by purchasing the markers of the "Burgler Bundle"
are hereby absolved of responsibility for any law breaking committed)
Trying to manufacture or sell that in the store would probably get you arrested (unless done in a valid parody form I guess?) similarly Facebook set up tools here to make it absolutely trivial to break some laws "Oh but we didn't realize we were breaking any laws officer" - welp, that's why newspapers and such have legal departments that review ads being placed in them, skipping that step to save money doesn't absolve you from guilt.