No, they don't "need" to do that. Not any more than newspaper, magazine or television advertisers "need" to know anything about the individuals seeing the ad, b

No, they don't "need" to do that. Not any more than newspaper, magazine or television advertisers "need" to know anything about the individuals seeing the ad, beyond the target demographic of the publication. They do it because there's money in it, but if website owners could put the welfare of their customers ahead of the relentless pursuit of profit by serving manually curated, static, untargeted ads we could have a much nicer web.