The Senate letter:

While a traditional search result or news feed links may lead users to the publisher’s website, an AI-generated summary keeps the users on the original search platform, where that platform alone can profit from the user’s attention through advertising and data collection. […] Moreover, some generative AI features misappropriate third-party content and pass it off as novel content generated by the platform’s AI.

Publishers who wish to avoid having their content summarized in the form of AI-generated search results can only do so if they opt out of being indexed for search completely, which would result in a materially significant drop in referral traffic. In short, these tools may pit content creators against themselves without any recourse to profit from AI-generated content that was composed using their original content. This raises significant competitive concerns in the online marketplace for content and advertising revenues.