The point of ad tracking is not to show ads that you need. It's to show ads that are likely to make you take the actions the advertisers need you to take. If the trackers determine that you have a gambling addiction and serve you ads for gambling sites, they're working as intended, but they're not helping you. If advertisers determine that their overall profits are increased by not showing ads for houses in desirable neighbourhoods to certain demographic groups, that's not good for the people in those groups.
