I am so tired dealing with these objections really. They only carry weight with people who are either innocently or deliberately ignorant of the state of affairs in Patristic literature. I mean doubts the authenticity of the short treatise called Philosophumena, or "Philosophizings" which identifies its author as Origen. This even though we have no knowledge of this manuscript from any ancient source. So what do scholars do to make it all better? They ignore everything the manuscript tells us about itself and re-baptize it as 'the Refutation of All Heresies by Hippolytus.'
The evidence that this text was actually written by Hippolytus is amazingly weak. Yet the Church Fathers mention a book of this title as having been written by this Church Father and so - presto alakazam! - everything is made better by transforming the text into something it never claimed to be. As Legge notes:
it would probably have remained unnoticed in the Bibliotheque Royale of Paris to which it was consigned, had it not there met the eye of Benigne Emmanuel Miller (= M E Miller), a French scholar and archaeologist who had devoted his life to the study and decipherment of ancient Greek MSS.
When you read through the life of M E Miller this nineteenth century scholar seems to have been engaged in the cataloging of manuscripts in manner uncannily similar to Morton Smith. We are told that M E Miller traveled about monasteries and libraries uncovering a number of 'one of a kind manuscripts' some of which - as we see in the example of the Philosophumena actually have no attestation in the writings of the Church Fathers and this should hardly be surprising. I doubt we even have in our possession one percent of all the books that were written in second century Christianity alone.