But to help you...
1. The issue here is ACCOUNTABILITY (especially for doctrines in dispute). IF truth matters in Christian doctrine (and there is passionate disagreement on that point), the accountability matters for the various positions among us, norming is thus embraced (norming of course is the evaluation of the correctness/validity/truthfulness of positions) and of course that include WHAT serves as the rule ("straight edge") or canon ("measuring stick") or norma normans ("the norm which norms") in such. All this you know.
2. The Rule of Scripture (what Luther and Calvin called "Sola Scriptura") is the practice of using Scripture as that rule in that evaluation of disputed doctrines.
3. This the Orthodox here have rejected. Curiously not for exactly the same reason as the RCC and LDS do, but by presenting an alternative rule - one that is MORE inspired by God, MORE inerrant, MORE reliable, MORE objectively knowable to all, MORE ecumenically (say by all 50,000 denominations) and historically (say to 1400 BC) embraced: TRADITION.
4. Well, but they don't. Because according to the RCC, that Tradition - INERRANT Tradition, APOSTOLIC Tradition, coming right from all 13 Apostles - TRADITION teaches in the most bold and clear way that it is de fide dogma (the highest level of certainty and truth) that the Bishop of Rome is infallible, Purgatory, Original Sin, Transubstantiation, the Assumption of Mary, the Immaculate Conception of Mary, etc., etc. DOGMAS. Right straight from TRADITION: lock, stock and barrel. Every Catholic bishop in the world would confirm that reality. So, if Tradition is clearer, more objectively known to all, more reliable and more inerrant than Scripture - why doesn't the EO go by it? (I could add Anglican Bishops talking about Tradition and Mormon Bishops talking about Tradition - but I think you get my point now). Sure you do.