Seems most of your list boils down to “Why do they believe scripture is more important than what the Pope says?” And that is easy to answer:
“1.19 And we have the prophetic word more fully confirmed, to which you will do well to pay attention as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts, 20 knowing this first of all, that no prophecy of Scripture comes from someone’s own interpretation. 21 For no prophecy was ever produced by the will of man, but men spoke from God as they were carried along by the Holy Spirit.
2.1 But false prophets also arose among the people, just as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Master who bought them, bringing upon themselves swift destruction. 2 And many will follow their sensuality, and because of them the way of truth will be blasphemed. 3 And in their greed they will exploit you with false words. Their condemnation from long ago is not idle, and their destruction is not asleep.” - The Apostle Peter
The Word of God takes priority over the words of men. And there have been an ample number of evil Popes, whose lives proved the Holy Spirit was not in them. There are also an ample number of evil men preaching in Protestant pulpits, and we need the Word of God to save us from being beguiled by their lies and deceit.
“All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, 17 so that the servant of God may be thoroughly equipped for every good work.”
Given that the New Testament church had no priests other than the High Priest, and the universal priesthood of believers offering a sacrifice of thanksgiving and good deeds, it seems reasonable to question the teaching of men who set themselves up as mediators between man and God...
Read the Bible, Jesus and the Apostles also believed scripture was the answer, not some human authority.
“Seems most of your list boils down to “Why do they believe scripture is more important than what the Pope says?” And that is easy to answer...”
Ding ding...we have a winner for theological strawman of the day.