The manipulation is subtle, but even if we assume ads don't manipulate you at all, they do manipulate people around you and shared societal consciousness - and that definitely impacts most people.
It's hard to call the de beers advertising campaign as anything other than manipulation. Maybe the worst example of the set of all advertisements, where the best would be advertisements that only explain what a product is, and where you can get it.
The problem is, Advertisers don't earn their paychecks by being honest.
