Google is about advertising. And SEO. The "sources" are generally what their algorithm considers to be 'good sources' but we have no indication that they have any validity. It remains to be seen whether AIs can somehow validate whether a source makes sense. "Reputable" at this point is irrelevant for anything except breaking news. Even in academia, citations dont mean much other than "this person knew how to promote their work well". We live in era of too many citations/references , and that has been detrimental. If we are going to be using machine learning from now on instead of 'reputation' , that is a good thing. At least we can know transparently what are the objectives the ML system is optimizing