Do you contend any post-scriptural speakers are superior, or equal, to those who wrote Scripture?
If “yes”, then kindly detail one post-Scriptural teaching on par with Scripture, and why we should elevate & append it thereto. (Something which, presumably, does not contradict nor claims exemption to Scripture.)
All authentic dogmas are rooted in the apostolic tradition: they are received from the mouths of the apostles who knew and were taught by our Lord in his earthly life. We have scriptural authority for the belief that the apostles received teachings not conveyed to the disciples at large. We search the writings of the Fathers to discern authentic apostolic tradition, as opposed to a theory or speculation.