> "I am not convinced it is that useful to have explicitly targeted audiences for advertisement. It may be better to understand and interpret an ad campaign, but generally, what works best when doing statistical prediction is not what is the most intuitive."

If you've collected marketing data that tells you your conversion rate among pet owners is 2% when your conversion rate among the general public is 1%, then you know that every ad you show to pet owners is going to have twice the impact on your bottom line.

Ad targeting enables you to collect this kind of data and to exploit it once you have it. If you find the right audience, your advertising dollars can go more than twice as far.