More people have more access to more readers for less money than ever before in history. It means a lot of dross but it means a lot of very talented people can find and nurture a readership in ways that were not possible twenty years ago. From a creative perspective that is all that writing is about.
In any case his judgment and set of values acting alone or through his assistants determine not only what is gold and what is dross but the design of the history which he creates out of the metal. The historian decides what is significant and what is not.