You seem to assume that everything that came from under someone's pen in the 1st century was divinely inspired (or as you would probably put it, described the historical Jesus). The early church had to look into the consistencies or lack thereof between documents, its oral tradition and its own, historically developed theological norm. Stuff that got rejected, -- typically the Gnostic writings, -- was at odds with the Epsitles, the earlier Gospels, the common sense, and with some fundamentals of the faith. For example, the notion of Jesus as a supernatural divine being locked in a struggle with the evil Old Testament Jewish God -- while evidence is plentiful that he slept, ate, was tired, irritable, felt pain, and kept a pious Jewish attitude through it all -- is clearly a fantasy.
The Apocalypse comes from a credible source and contains normative Christian eschatology, consistent with the eschatological vision in the Gospel parables. It also correctly predicted the destruction of the Jerusalem Temple and the emergence of the Chruch Triumphant.
Or correctly reported, at any rate.