You’d have to handle disagreement about just what everybody, everywhere... believed.
Putting that aside, you had major disagreements and heresy going on. Those wouldn’t fit your method. To take one major example, who Christ was/is. Would you accept the decrees of the First Council of Nicaea? Arius or Athanasius? Would the dogma Arianism be ok? You end up violating your criteria one way or the other.
The Church accepts the Council.
Yep, I like Athanasius’ example. Great demonstration of Prima Scriptura Contra Mundum. An early version of us, except that in those days the magisterium could still reverse itself based on Scripture.
BTW, this comment is necessarily hit and run, as I am at work and don’t have time for a full brawl. :)
However, I love to peek in every now and then, so carry on ...
Peace,
SR