That being said - and it pains me to say this - but there is absolutely truth to the fact that the style of targeting now possible on FB & Instagram has enabled an entire world of very small, hyper-niche businesses that otherwise wouldn't exist.
Ten years ago, there wasn't any way to reach very granular audiences the way there is today. There was massively broad and massively expensive brand advertising, there were poorly targeted display networks, and there were effective but prohibitively expensive direct response channels like AdWords - none of which were viable if you were selling, say, dog leashes to people with a penchant for the outdoors.
That isn't to dismiss Facebook's culpability for the liberties they take with their users' personal data, and they certainly didn't build their ad network out of altruism for small businesses, despite what you may think from the position the ad takes. Facebook's access to user data should be curtailed significantly, and sadly, businesses likely will suffer. There doesn't seem to be a good, evident third option just yet.