Definitely that's the reason the ads are cheaper in less developed and less wealthy countries. It's simple supply & demand: obviously there are more people targeting ads towards users in the U.S. and other wealthy countries.

We touched on a lot of this in the article, and in fact the title clause "(and why you might not want to)" was referring specifically to that point!

That being said, there is a tremendous amount of useful techniques you can learn from this approach, and you can choose apply those towards whatever demographics you are marketing to.

It's up to each person to decide the specific goals of their ad campaigns, but I'm hoping this article outlines some techniques that will help you achieve those goals.