Couldn't Facebook easily demonstrate causality by running an RCT? Just randomly select half of a certain demographic to show the ad to, and then show that those users are more likely to make a purchase later.
Theoretically yes, but I think with standard Facebook ad units and regular consumer brands sold in stores they'd be pretty unhappy with the results...
(since probability of giving stores your contact details post purchase and susceptibility to marketing messages pre-purchase are probably positively correlated and Facebook is permanently running concurrent trials of different kinds and being very selective about what they share, any positive effect they did manage to identify should be viewed as an almost certain overstatement of the ads' actual effectiveness anyway)
(since probability of giving stores your contact details post purchase and susceptibility to marketing messages pre-purchase are probably positively correlated and Facebook is permanently running concurrent trials of different kinds and being very selective about what they share, any positive effect they did manage to identify should be viewed as an almost certain overstatement of the ads' actual effectiveness anyway)