You would assume that Advertising companies with quality ad space would be able to show higher click through rates and higher impression to purchase rates -- overall cost per conversion -- by removing bots that won't have a business outcome from the top of the funnel.
But attribution is hard, so showing larger numbers of impressions looks more impressive.
Attribution is extremely easy, it is a solved problem.
Companies keep throwing away money on advertising for bots and other non-customers because they either:
A) Are small businesses where the owner doesn't care about what he's doing and enjoys the casino like experience of buying ads online and see if he gets a return, or
B) Are big businesses where the sales people working with online ads are interested in not solving the problem, because they want to keep their salaries and budget.
But attribution is hard, so showing larger numbers of impressions looks more impressive.