My thesis is that marketing doesn't brainwash people. You can use marketing to increase awareness of your product, which in turn increases sales when people would e.g. otherwise have bought from a competitor, but you can't magically make arbitrary people buy an arbitrary product using the power of marketing.

so you just object to the semantics of 'brainwashing'? No influence operation needs to convince an arbitrary amount of people of arbitrary products. In the US nudging a few hundred thousand people 10% in one direction wins you an election.

This. I believe people massively exaggerate the influence of social engineering as a form of coping. "they only voted for x because they are dumb and blindly fell for russian misinformation." reality is more nuanced. It's true that marketers for the last century have figured out social engineering but it's not some kind of magic persuasion tool. People still have free will and choice and some ability to discern truth from falsehood.