I think it’s a stretch to suggest that Facebook’s targeting technology doesn’t work, considering that the advertising is a trillion-dollar industry across the world. I personally find it a stretch to believe that advertising doesn’t work given the huge amounts of money that go into it. And I find it a stretch to think that the more information you have about individuals and the more …
The more time I spend in the tech industry, the more often I see things that don't work at all (or barely work) getting enormous investment. When your industry is highly financialized, hype is an effective substitute for functionality (at least when it comes to your bottom line). This is especially true when it is difficult to determine effectiveness. Advertising is an industry where reliable, unambiguous measures of effectiveness over time are really difficult to produce, and targeted advertising involves adding a whole set of complicated factors (not in isolation) to any such experiment. So, it's very easy for claims of improved ad targeting to make money without being remotely true.
From the other side (the consumer side), we can measure it more easily, and it doesn't look good. Have you ever bought something via a facebook ad? Has anyone you know ever done so? I've used facebook since 2007, and I've bought a grand total of one thing (a ten dollar t-shirt) from a facebook ad, and I have never bought something from a google ad (despite google having much more information about me and much more research into ad targeting). It'd be foolish for any of us to think we are more savvy or immune to advertising than average. We are probably precisely average -- which makes ad targeting very bad on average. However, if you can claim that your new tech ought to be marginally better at targeting -- and every business that spends money on advertising knows that this can't be proven one way or another -- many of them will be willing to buy your targeting tech, especially as practically all online advertising is algorithmically targeted (meaning that the least expensive forms of advertising are also the ones using this tech).
If I buy gas station sushi, it is not an indication that gas station sushi is good. If gas station sushi is more profitable than boutique sushi, that's not an indication that gas station sushi is better than boutique sushi. It's an indication of price point and availability: I have five dollars in my wallet and feel like eating sushi, and this is my only real option. Adtech is the gas station sushi of the internet.