Even with targeted ads how often is it that someone actually (1) wants the thing and (2) buying the thing is net good for them and for society? I'm sympathetic

Even with targeted ads how often is it that someone actually (1) wants the thing and (2) buying the thing is net good for them and for society? I'm sympathetic to the argument that ads could reduce information asymmetry, make the market more efficient, and thus count as a social good. The problem is that advertisers' incentives aren't the same as society or the consumer's. Look at it this way: Google exists. If you know you want something, it's not hard to find online. Ergo, if you often find yourself buying something because you saw it in an ad, what does that say about your rationality as a consumer? In practice, corporations buy ads to manufacture demand because their products are neither things consumers or society actually wants, nor things consumers rationally choose to seek out.