The economics wouldn't shake out if it didn't work. Just because they don't work on you personally doesn't mean they don't work.
It's quite hard to track though some progress has been made through tracking you online on longer time scales. Most people dislike this type of tracking across channels cause we really don't get much out of it besides being bombarded with ads from the same company.
Exactly. Coca-Cola and McDonald's didn't become billion dollar companies by not advertising.