Honestly, I'd guess it's just laziness and/or naivety; one publication does a story and puts in their referrer link, and then the person at the next publication

Honestly, I'd guess it's just laziness and/or naivety; one publication does a story and puts in their referrer link, and then the person at the next publication just copy/pastes the link they found to the first story rather than doing the extra work to get the direct link. Then the next publication sees that story, and pastes a link to that one, etc...