You keep saying that, but that is plainly a positive spin on the purpose and not completely truthful.

If that were the purpose, why are there adverts for e.g. milk?

I don't see how this squares with things like blatant scare mongering smearing in political ads, and things like cowboys riding a truck up Mt. Everest to crack open a beer.

Ads can be there just to associate emotional moods and undertones with a product or person, etc., and aren't only about surfacing unknown products.