Having been a Protestant most of my life, I can answer this. Protestants see Catholic and Orthodox leaders as among the wolves who preached a "different gospel", and led the early Christians away from the simplicity of the gospel recovered by the Reformers.
-A8
A ‘simplicity’ that historically only manifested in the 14th century. (Amoung other things, since you’re concerned about the old testament judaism, protestants arbitrarily do away with God’s prescriptions on the priesthood.)
If one must trust the authority of one's own church leadership & that the Holy Spirit only protected them (everything that they teach as dogma), the possibility that the wolves had corrupted your church would be blasphemous.
Anyone seeing the church as having lost it's way & riddled with corrupt wolves must deny one's own lying eyes. Going back to the beginning, to see what the basic foundation looked like is fruitless to anyone who thinks there have been no changes since then that haven't come from the Holy Spirit.