It is indeed an interesting example of information asymmetry. An economic historian at LSE who I know actually traces the origins of modern advertising to the rise of "brand-name" medicines. Back in the late 17th century, early newspapers started running early ads for proprietary drug recipes that cured things like plague and gout. These were the earliest products to be sold via mass media and to be "branded" using the name of the preparer. I.e. in a world where a consumer would simply go to "Shoe Street" to buy shoes, these early apothecaries pioneered the idea of using mass media to persuade consumers not to buy a generic gout cure, but instead to go specifically to, say, Mr. Merck's shop to buy "Merck's gout elixir" (I use that example because the Merck corporation actually does trace its origins to a late 17th century apothecary).