Is There a Necessity for Advertising?

Every company that competes in selling bananas, hypothetically, or whatever other focking commodity, are all spending, in their individual budgets, on different advertising campaigns to convince you that my banana is better than that due to banana. 99 % of the differentiation between most brands is, quite literally, in their advertising and positioning of how they're perceived by by their given market demographic. Most corporations do not create a product and then start pitching it to whoever happens to most co identify with the given type of banana. So yes, this is a massive amount of capital which goes towards something that is, quiteliterally useless. But why is there this necessity for advertising? It's because there are so many