Comment by embedding-shape

You're looking for evidence that providing external links might lead to users visiting those external links? I'm not sure what you're doubting here, it's a pretty typical "web user behavior", if you've ran a website before. Any exit points you provide leads to more users leaving at those points.

The KPIs these websites use to measure "how good an article is" is (among other things) how long time people "spend" on the article. Remove all external links, and it'll at least look like people engage for longer with the content. Does it make sense? No, but won't stop the people who run the business to believe so.