I questioned Thucydides. You start with one statement and pass it along to, let us say, ten people. By the time the statement gets to the tenth person it is completely different from the first person's statement. It is very much how gossip works. Karen went to the store to see her boyfriend who she caught kissing another girl.
History is no different from the telephone game.
Accuracy is lost in the exchange. You end up with something almost completely different from what you started. That is not the only problem you run into. An additional problem is if a person has a bias against a particular person or group of people. Let us say that I did not like Karen and added the piece about her seeing her boyfriend with another girl.