The reason reputable news organizations put in place their verification and validation processes is because most people are not aware of their internalized biases and do not willingly challenge their internalized world view. Since they won't do it themselves, the organization must do it for them.
And if the organization fails to police their own standards it is the organization that suffers loss of credibility. Publish enough unverifiable rumor and innuendo and it becomes THE NATIONAL ENQUIRER. Or at least Slate.
