I don't agree with the « not because people don't acknowledge the bias » idea (which is quite recurrent in the post). People who give credit to O'Reilly don't think he is biased. They think the rest have a "liberal bias", and that O'Reilly is himself neutral and accurate. To us it seems that they give credit to O'Reilly because he's openly biased, but to them they give credit to him because they consider him to be less biased than average.