Ads aren't always there to get you to buy something specific. In fact, an ad you don't interact with is a better ad because they don't have to pay for click-through.
You don't want to buy brand A because they have ads, so you buy brand B instead, but both widgets are owned by the same holding company. Or they're made in the same factory. Or they use the same components. Or they have the same shareholders. Any way you slice it, the same rich assholes are getting your money.
The goal of the Ads is to put a bug in your head and get you to buy something.
And that's just the Ads. The tracking is also (increasingly primarily) about political manipulation and surveillance.