Original sentence: It is claimed that if not for that, the expulsions could not have occurred.There is a minority perspective which argues that blame is also shared by the Germans who supported the Nazi regime, because of the way they treated other peoples, including Jews, Poles, Russians and others during the war
Edited sentence: There is a minority perspective which argues that blame must also be shared by the Nazi regime and the Germans who supported them, because if not for those Germans, the Second World War, and this event, would not have occurred