But there has to be some reason for original source links never appearing in journalist articles.
And there's also the idea that you should be able to at least somewhat trust the people reporting the news so they don't have to provide all of their references. --You can certainly argue that not all reporters can or should be trusted anymore, but convincing all journalists to change how they work because of bad ones is always going to be hard.
Reputable news organizations are more robust against such pressures, but plenty of people get their news from (in some cases self-described) entertainment sites masquerading as news sites.
So they rarely are forced to do anything but state the name of who they interviewed, and that's it. And puts them in the habit of not acknowledging what they read, as a source?