Publishers already stuff as many ads in the space they have as viewers will tolerate, so it's unlikely that a reduction in fraud will result in consumers seeing

Publishers already stuff as many ads in the space they have as viewers will tolerate, so it's unlikely that a reduction in fraud will result in consumers seeing more ads. If anything they'll see fewer ads, since the existing ad space will become more valuable. The fact that ad space is primarily sold in the form of real-time auctions, and advertisers can track end-to-end results online (e.g. "we generated $10 in new sales per 1000 impressions last month") ensures that the price goes down when there's more fraud and up when there's less. Undetected impression fraud leads to publishers earning less for their legitimate impressions, not advertisers paying a premium.