From the Greek ochlokratia, from the Greek ochlos (mob) + -kratia (-cracy): government by the mob, mob rule. Example from an esteemed member of the MavPhil Commenter Corps: "I just tell my students and anyone else I know not to read the Wikipedia article [Philosophy] except for a laugh. It's one of those areas where the ochlocratic nature of Wikipedia really comes a cropper."
In case anyone is unclear, and I was, 'to come a cropper' means to fail badly, to get caught out, to fall.