Who's desire does it fill? My rational system 2 brain? Or my impulsive system 1 brain. The reason you can't justify shitty content with "we're just giving you what you want" is because we really want something better, but if you give us shit that appeals to our impulses, you can make us act against our best interests. So we keep scrolling through the news feed at 2AM, thinking we should really go to bed, but failing to resist the feeling that some huge payoff lies just a few scrolls down.