Yeah, it's the lack of attribution that is key, even if it sounds like a trivial and ceremonial step. If a New York Times reporter writes "'Our investigation has completely stalled,' Kings County Sheriff Bob Jones told the Springfield Observer", I can infer that the NYT is reliant on local reporting for this story and may not have done original on-the-ground work themselves.

Imagine how flimsy Ars' story about a blog post would look like if the story had correctly attributed the quotes (fabricated or not) to, "according to Claude AI's analysis of the blog post". The reader would have the right to wonder if the reporter had even read the blog post.