The 1% chance you will click on a singles ad is worth more to Facebook than a 90% chance you will click on an ad for your favourite hobby. The singles company will pay higher for that 1% click chance than anyone else. Even if Facebook could show you a more relevant ad, they are not incentivized to do so.

It doesn't matter to Facebook/Amazon whether or not they show you ads you are interested in (or that might impress you with how deep they understand you as a person). It only matters if advertisers get better results than they would get by spending their ad money on TV, Newspapers, Magazines, Radio, etc.