They show what is possible
Whether they are positive or negative, they cannot be dismissed.
As a personal example: My former lawyer graduated from a mediocre university, he was a mediocre law student, and he went on to become a leading high profile lawyer listed as distinguished on the Lexis Nexus Martindale-Hubbell peer review. He and his moronic law clerk destroyed my case, my health, my access to medical care, to compensation, and to justice. And I was a special client who he claimed to like...
Other leading lawyers want me to report him. But even though I haven't yet, he knows what I am capable of, and he is petrified of what I would do. He knows that I do not intend to let him do to others what he has done to me...