The part about cause and effect was very interesting. So possibly Facebook knows if a user is likely to buy something from a specific company and it will show

The part about cause and effect was very interesting. So possibly Facebook knows if a user is likely to buy something from a specific company and it will show an ad to them in order to boost their conversion numbers to fool the advertiser about the effectiveness of the ads. But the ad has no effect other than to artificially boost conversions. It doesn't achieve what it was paid to do; to convince users. It reminds me of the old saying that merely finding a way to measure a trend has the side effect that it allows people to game that trend.