This point is often repeated during discussions on these topics but I believe this is an inaccurate characterization. YouTube is not "in charge of deciding what is credible" in the fashion that kind of phrasing suggests; they are moderating the content on their platform with respect to their business process and company values, those decisions are not a reflection of credibility. YouTube is a corporate product and we should not encourage the narrative that this product is the zenith of knowledge even though there are knowledgeable people who put content on YouTube.