"Knowing everything about a user does not make them a better customer"
Making idiotic misuse of the info does even worse. You just bought a bed online, so for weeks you get ads for beds thrust at you...
The real dirty secret is that none of this snooping is for the benefit of advertisers or you - it's primarily for the benefit of the ad brokers. They make money regardless of the effectiveness of the advertising.
Biting the hand that feeds IT
