I have been considered too young to credibly and authoritatively state the views that I do. The only prejudice is content. Ultimately, understandably but wrongly, we are trying to reduce the need to find out for ourselves and make our own decision about someone's worthiness. I can understand why using resume information does establish credibility quickly. Have you noticed how it is always mentioned in articles when somebody studied at Harvard or Oxford.
Credibility is unrelated to titles, qualifications or experience.
Whether we consider someone else's views and ideas credible is a product of our own intelligence, investigation and impartiality. When I weigh up the value and importance of new ideas on my thinking, I consider other points of view, my own discoveries in relevant areas of my life, the underlying theories and patterns and the ideas not their originator. The ideas matter, not their source. We need to rethink what constitutes credible sources in the unorganized world- and be prepared to keep an open mind and think for ourselves what we think of that particular content whoever originated it. At the end of the day, I think, therefore I am.