It turns out to be the other way around: the site owner claims that the ads Google served up were of such low quality that they "polluted" the content of the site:

"For about R20,000 a year, it isn’t worth it to pollute our content with get-rich-quick adverts featuring Patrice Motsepe, Richard Branson and Oprah Winfrey (see image at top of article)."

Moreover, the author states in the comments that their non-profit is sustained by donations, not by ads. If someone had visited this site with an ad-blocker turned on before the author stopped using Google ads, it would have improved the content (by the author's own stated standards) without endangering the site's source of funding.

Granted this may be a special case. But I think special cases are often worth the read, or at least not "just like any other kind."