What do Wikipedians and Mel Gibson have in common?
They think they have a clue about history and really don't care if they get things entirely wrong as long as they agree with their friends that they're right. And that other people believe them.
At least it's so bad that if I don't catch my students plagiarizing it, I can still flunk them for using really, amazingly, pathetically wrong information. Because, yeah, we all know that the Carolingian Empire and the Holy Roman Empire were one and the same. Er ... yeah.