Point. But I'm not going to discount the non-zero effect they likely still have on my reasoning for choosing certain brands when all else is equal.

that's a fundamental misunderstanding of marketing. you probably subconsciously remember some of the ads, and even assimilated some of those messages into your psyche without realizing it. these probably manifest in ways like when you want to buy something and can't help but seem partial to a particular brand even though you're not sure why.