I think it's based upon the idea that people with ad blockers see less ads and so are still sensitive to ad impressions. In contrast, advertisements in really crowded situations (most people that walk about in urban areas, for example) require more effort to stand out as advertising saturation point hits.

I mostly combat any ad influence on me by making a point to _not_ buy anything that is advertised. Works out pretty well for helping me keep my sanity and conscience a little.