I think that Miller is suggesting that while what is being written should be seen as a drama, it is historically real. Miller does not deviate from the history being written. Rebecca Nurse and John Proctor were killed. Corey was pressed to death. The girls escape punishment for their actions. All of these are true. Miller does not use his ability as an artist to change their fates. Rather, the drama is embedded in history. Doing this accomplishes two purposes. The first is that it beings an even weightier gravity to the work, in that the horror of what happened is magnified by its reality as history. Additionally, it enables Miller to make a historical point about politics and power. The idea here is that Salem demonstrates what happens when a lack of institutional checks is present and what happens when individuals fail to think and enable others to think for them. In this, Miller is able to draw immediately paralels to the McCarthy time period as well as to Nazi Germany. In being able to rely on the "historical model," Miller is able to make the argument that this is not in the hands of the artist to recreate, but rather the story teller to relate to the audience.