An advertisement that happens to reach someone who has a problem that your product solves isn't a scam. It is a way to get that person to know about your solution.
It's like a city was proposing to limit car movement through the center to improve air quality, and you countered with "but some cars are electric and don't pollute!". Yeah, right. Wake me up when most of them are.
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[0] - See this subthread: https://news.ycombinator.com/item?id=21348886.
did the creator of the X pay a third party to present X? is X an essential part of its context? is the recipient of X seeking X itself or something else?
I don't think the parent poster meant absolutely all ads, just the vast majority of them. But in so far as they meant all ads, it's still a good point you shouldn't trust them - not even the product catalogs you yourself paid for. There's very little legal and social protection from the merchant lying to you, and all the business incentives to do so.
Also, the print newspaper industry isn't as clean as you think.
http://paulgraham.com/submarine.html
You shouldn't be trusting any ad, wherever it is. Actually, the most reputable the platform, the more skeptical you should be since you are more trusting of the platform to begin with. The easier you are to be duped.