Don't assume the cost of the infrastructure for privacy-invasive advertising is free, or that it's just automatically easy to do such things once you're offering some other user-facing service. Acquiring, storing, correlating, and sharing all of that user data is very expensive in architectural terms. It will vary by business model, but I would imagine anywhere from 20-80% of operating costs go out the window if you architect your systems to only offer the services users actually wanted.