Is audience engagement media effects studies in disguise?

I somehow get the sense from reading Napoli's discussion on "engagement" that maybe what is really of interest is "media effects" from Communication. Specifically, how effective advertisements or product placements are in leading to purchases (p. 98). 

In the field of Communication, at least in terms of scholarly conception of media effects, we have witnessed the shift from "powerful effects" (i.e., the magic bullet theory), "minimal effects" (i.e., limited effects) to "moderate effects" (i.e., contingency effects). While the debate is on-going, there is general consensus that mass media are not all-powerful, but that their effects depend on many factors such as audience characteristics, environmental influence, medium specificity, etc. 

It sounds like most media professionals still operate under the powerful effects paradigm in their attempt to understand and measure audience behaviors, and perhaps it is in their best interest to believe in such a framework since they've already poured so much money into the business, but what if they are wrong?  What if, like Communication scholars find, powerful effects don't exist? 

Regardless of how advanced audience metrics or how fancy advertisements become, audiences are evolving at the same time too. Such co-evolution will always, at least I'd like to believe, thwart media effects because we learn to adapt to the new environment to minimize unwanted stimuli (e.g., how many of us really "see" pop-up ads these days anymore?). In a way, maybe this suggests that audience metrics will never be satisfactory to advertisers if their ultimate criterion is to be able to perfectly identify and measure factors that influence purchasing behaviors. 

Perhaps I am overly simplistic in making this statement, but on some days I think maybe the only "media effects theory" that really counts is priming (in the sense that some scholars argue agenda-setting is a kind of priming effect, and framing is not a 'theory' per se), and I wonder if advertisers are doing themselves a disservice whenever they deviate too far from the basic principles of priming in their attempt to manipulate human desires and take over the world...