Do you mean the advertising company that runs a search engine should punish pages in the results that... show their ads? Or just when it's a "lot" of their ads? Or should they only do that if the pages are showing ads from their competitors?
I’m honestly surprised that Google thinks that a page with N ads deserves N times the CPM. The more ads, the less attention each ad can grab, no? I wonder whether just treating ads as zero sum (regardless of ad provider) — such that a page with 5 ads, 2 of which are Google ads, gets a payout of 2/5 the CPM of a page with one Google ad and no other ads — would basically drive all these SEO mills out of business. While also not really impacting honest ad-sponsored sites (like Reddit), that only tend to run one ad per page.
