Besides encouraging people to buy things you might think they don't need, what's an actual harm people experience from targeted ads as opposed to non targeted ads?
Targeted ads are used to target people at their weakpoints: pushing people into addiction, spending money on questionable health remedies, ... - and from what I hear from people in publishing industry, basically nobody is effective at policing this kind of thing, but rather takes a "oh to bad, if you tell us the exact example we'll ban them maybe".
Data collection also creates additional resource usage which makes user experience worse.
All you have to do is go to the wrong page and a day later you have ads for things you have no interest in. It happens with HN, where I click a post and then see ads I'd rather not.
And then consider what needs to happen in order to target someone so personally or individually.
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Question to someone in ad tech, do your customers lose greater than or less than 50% of their ad spend to targeting the wrong person, malicious bot nets used to syphon from the system, and / or other sources of loss?
We will email you and call you with ads and offers based on what we think you will like.
We promise not to do anything bad with your personal information."