The harvard link touches on how he was using cheap Google Ads for this purpose. It reminds me of a shady "internet background check" company that I had the unfortunate pleasure of working with a few years ago. They were approaching, if not exceeding, this site in total shady tactics. One thing they did that their former-pill-pushing founders came up with which I did think was rather clever is they were able to buy Ad Words for cheap for various permutations of common given names and they used this to bootstrap their business to great effect.
Facebook does not allow you to build a custom audience of 1 person. I believe it has to be a minimum size of 100 or thereabout. Which means when Spinner says your target will get 180 impressions, they have to throw in 99 random non-targets into the targeted audience in order to get the placement. Thus they really aren't marking it up as much as you think.
They would batch them though, wait for 100 clients who want the same and put them in the batch. So it does provide a marginal service, viewed from that angle.