Add advertising execs to the list of people responsible for the proliferation of AI-generated content, because in the end, they're the ones paying for it.

Blue-chip advertisers spend $13 billion annually funding "MFAs" (made-for-advertising websites) publishing fake news, conspiracy theories and other unsavory content, according to a new ANA report on the $88 billion programmatic marketplace.

UGC now accounts for more than a quarter of all ad spending -- up from less than 10% just six years ago, according to a unique new analysis from GroupM.

While economics and market fragmentation are big factors, it also has a lot to do with the KPIs marketers use to benchmark business outcomes.