This is only true for established brands, selling products that don’t change, in saturated markets. Even then it’s only partially true, because the markets themselves are always changing (chances are at least somebody in the world drank a coke for the very first time today). It also doesn’t account for the fact that even if all those factors are truely static (or close enough), that product differentiation strategies can still be used successfully (which is again something you see coke doing a lot). That paradigm really only applies to a very specific type of advertising, under very specific market conditions, and doesn’t apply to the majority of the worlds advertisers.