No, but if you're a brand marketer, you need to be able to perform demand planning. If $(ad spend) > (impressions) * (conversion rate) * (price) then you do it.

No, but if you're a brand marketer, you need to be able to perform demand planning. If $(ad spend) > (impressions) * (conversion rate) * (price) then you do it. You can't get around counting impressions. But it's not important that impressions are accurate; just that they behave roughly like they have in the past. What the article is saying is that there's an upper limit on the amount of fraud that can be perpetrated without showing up in other metrics, and at current prices, brand marketers just don't care. Because brand marketers don't care about impressions; they care about P&L at the brand level. If a banner ad campaign drives top line brand revenue, that's all they need it to do.