Perhaps you are mistaking an early conclusion of preterists for a founding principle--an honest mistake on your part, and one that is strengthened by the things most preterists say. I could be wrong here, too--I don't really know the motivations of preterists.
Preterism holds that the contents of Revelation constitute a prophecy of events that were fulfilled in the 1st century. Preterists believe the dating of the book of Revelation is of vital importance, and that it was written before the destruction of Jerusalem in 70 AD. Preterism was first expounded by the Jesuit Luis de Alcasar during the Counter Reformation, it affirms all eschatological points of the ecumenical Creeds of the Catholic Church.