Targeted advertising works and delivers better results than non-targeted advertising. This has existed for pretty much as long as advertising, way before the internet.
I am not expert in the field but I am sure that there are hard data from studies available on the subject.
A question is whether it is worth paying the extra money to run a specific campaign on a specific platform and the answer is, as often, "it depends".
They are not contradicting. I'm just saying that I don't have references to studies on hand, but I'm sure that they are available because, well, targeted advertising works (Hardly a ground breaking claim, that is pretty much established for a hundred years at least, and you can run your own campaigns to convince yourself).
I agree that targeted advertising worked to some degree, you wouldn't advertise a Rolex in a suburban housewives magazine, a luxury yacht in a gardening newspaper or a cheap alternative to butter in a cooking weekly.
Today's online targeting have two flavors AFAIK, one resembles the old way of putting an add in a place where we expect people to react to it. The other works differently, they try respond to search terms or site visits and my feeling is that this kinds doesn't work so well.
I am not expert in the field but I am sure that there are hard data from studies available on the subject.
A question is whether it is worth paying the extra money to run a specific campaign on a specific platform and the answer is, as often, "it depends".