It is rationally rational to cite your source even when you say: My coffee is currently hot.
We must judge. This criterion is logically wrong.
We need to know the debater is not just making everything up, but is informed about their arguments. Of course, we don't have to cite everything, but the most debatable issues should be backed up.
Can't tell who lost some sources points recently.
Sources are only a means of supporting some facts in the arguments.