Have you really never bought a product or service for some other reason than that you saw an ad for it?

People have plenty of other ways of finding out about useful products and services. You can talk to your friends and family, or go to a store and talk to a salesperson, or look up product reviews online, or even pay for something like a Consumer Reports subscription.

Friends and family can be influenced, although I'd still trust them above anyone else. But salespeople are incentivized to lie to you (sorry, it's true). Product reviews are astroturfed by bots now. Consumer Reports, too, has been captured by industry, and is largely useless now.

When the metric is "make sales and make as much money as possible", it will be incredibly difficult to avoid bias from people with a vested interest in selling you something. This is why advertising (admittedly, mixed with our current society) is so insidious: it's very hard to find a third party that isn't trying to profit off of you buying something.