Which collects data on you and creates a profile. Whether it's currently used to increment an impression counter doesn't mean it can't be used for something more nefarious down the line.
Collecting data about what you did is not necessarily spying. If a game keeps tracks of my wins. That's not spying even though it's collecting data on what I did.
It's not just about telling if an ad has been seen, but what a user does on your site after clicking on the ad. Do they immediately bounce? Do they buy something?
You want to be able to see that you are actually getting a positive return from the money you are spending on ads.
