The ad industry is really secretive in general. There aren’t many studies proving that targeted advertising even works. If the data was even slightly in the ad industry’s favor, they’d release it. Their entire job is spinning things to look good.

I suspect that targeted advertising was invented to justify the existence of advertising companies as middlemen. Take for example the ExplainXKCD wiki. They just serve their own ads which are usually for tech products trying to reach Sysadmins. If every company did this, the ad industry would wilt.