I understand they use adverts, but that doesn't mean they need to know everything about me.
As DuckDuckGo put it, they display adverts by displaying relevant ads based on searches. You searched for a car? They display car adverts. You searched for a book? They display adverts for a new novel.
They don't need a track of and psychological analysis of every person's habits.
Yeah I can't imagine I would have hit accept myself but can't think of any other reason I'm not seeing that. Definitely not getting any argument from me about tracking though - I don't know why anyone is okay with it.