The Accuracy and Reliability of the New Testament Gospels?

Why do so many scholars hold so strongly that the New Testament Gospels, particularly the Mark, Matthew and Luke, are more accurate and reliable for reconstructing history than the non-canonical when it was proven by Professor Wrede in 1902 (The Messianic Secret) that the author of Mark was a theologian not an historian? The New Testament Gospels (and the apocryphal Gospels) are not histories, nor are they even historiographies. They are theological treatises whose main interests are Christological.

The New Testament texts don't have anymore intrinsic reliability for reconstructing the "historical" Jesus and Christian origins, than early non-canonical texts. The virgin birth stories in Matthew and Luke are no less legendary and fanciful than the account found in the Infancy Gospel of James. The miracle stories of Jesus in the four New Testament Gospels are no less fantastic than those performed by the child Jesus in the Infancy Gospel of Thomas. The passion narratives in the New Testament are no less contrived in order to "prove" that Jesus' suffering and death had fulfilled the Scripture than the crucifixion narrative in the Gospel of Peter. The account of the pre-existence of Jesus in the first chapter of John is no less mythical than the accounts of his pre-existence in the Gospel of Truth. The reports of the miraculous deeds of Peter, Paul and Philip in the New Testament Acts are no more reliable than their deeds recorded in the apocryphal Acts which bear their names. The wild apocalyptic story in Revelation is no more an account of the end of our world than equally wild descriptions found in the visions of the Pastor Hermas or the Apocalypse of Peter. The sayings of Jesus in the Synoptic Gospels are no more the verbatim words of Jesus than those recorded in the Gospel of Thomas, the Dialogue of the Savior, or the Secret Book of James. They are just more familiar to us because they have been part of the Christian tradition for so long. Has familiarity been mistaken for historicity?