The thing is that, as even you have pointed, many advertisements don't provide information, such as specifications. They are more about look and feel.
Ads will often use lingo, or scientific terms, or "feel good" phrases, not so much to induce a purchase, but to make a positive link to a brand or product. A purchase is almost a side benefit; advertisers want brand recognition first and foremost. I know plenty about Coke, I have even been to the Coke Museum (or whatever it is called) in Atlanta, but I don't drink it. I even kinda like the cute Coke polar bear ads, but it still won't convince me to drink the stuff. I recognize the brand, and for the advertiser that is half the battle; but not the winning of the war. The point is that when someone talks about drinking a Coke, I share a recognition of a sugary drink, and a will not confuse it with that tar-like industrial biproduct that goes by the same name. If you will, their advertising has expanded my "brand-literacy."
Neither you or I can convince all people to actually sit back and analyze everything that they are buying. It would be a good idea if more people actually did question themselves about what they thought they needed. Nevertheless, people can and will make a purchase for a number of different reasons, sometimes even contradictory reasons. And sometimes those contradictory reasons have nothing to do with advertising.