Where do I say that neoclassical economists ignore advertising? I might say it somewhere, but not in this article, as far as I can tell. The question isn't whether these economists have nothing to say about it, but whether their theory can easily accommodate these externalities. They're external in that these phenomena would only interfere with the idealizations that make up the model of the perfectly rational consumer. Advertisers assume, on the contrary, that we're not so rational, and ads work mainly on that basis. The better the ad, the more manipulative it is, and the more the consumer is made into a dupe. The more dupes there are in the market, the less efficient its operations, according to the neoclassical school.

Moreover, the fact that neoclassical economists can accommodate so many aspects of economics feeds the suspicion that their model isn't falsifiable or especially scientific. Theologians likewise have an answer for everything, which isn't necessarily a good thing.