No one has said it isn’t. The principal set down by Paul was that relying on oral transmission is not reliable and needs to be judged by the written word. Until the death of the apostles who were eye witness new information was relevant. After their deaths it becomes less and less reliable. The admonition to “search the scriptures to see if these things are true” still stands as sound advice.
>> But unlike the typical strawman of sols scriptura (SS), this does not mean that all that can be known is in Scripture, as that would be contrary to Scripture;<<
But I can assure that anything additional would agree with scripture in all respects.
>> Nor does it mean it must reject all practices otherwise loosely termed “traditions,” (wedding ceremonies, etc.):<<
I know of no non Catholic who has said otherwise.
>> And as per the latter, it provides for the church and its magisterium, among other things<<
Say what? It supports no hierarchical structure.
>> Sorry for the length, but i think some clarification is needed in this foundational issue of authority.<<
No one has said there aren’t traditions. There are local traditions, regional traditions and traditions which are nationwide. When Christ was denigrating the “traditions of men” he wasn’t talking about those. He was talking about the requirements for salvation. The “foundational issue of authority” only relates to the “elder” of the local Christian community who have grown in knowledge and the faith and the given gifts of teaching etc. No “organizational structure” for the “church” other than Christ as the head is given or implied. In every instance of increased “authority” with the leadership of the church on earth human greed and power has corrupted.
I do not think there was any real disagreement but so often SS is misrepresented by those who oppose it.
As for “it provides for the church and its magisterium..,” it does just that, of pastors, teachers, etc, in the interdependence of the body and its gifts and offices, and in which bishops/elders refers to one office of leaders/overseers among brethren, (Mt. 23:8; Titus 2:15; Heb. 13:7) and not after the vast Roman bureaucracy and its most reverend Lord Archbishops, etc.
As re “foundational issue of authority,” i was speaking of Scripture versus an office of men being assuredly infallible and supreme.