That's an excellent insight, Dr. E. I can see no other reason. It seems to me that Catholicism is dependent on an idea that God chose to transfer great power away from Himself and install it into certain men. In the OT, it appears that God was fully content and up to the job of executing His role as sovereign Himself:
1 Sam 8:6-8 : 6 But when they said, "Give us a king to lead us," this displeased Samuel; so he prayed to the Lord. 7 And the Lord told him: "Listen to all that the people are saying to you; it is not you they have rejected, but they have rejected me as their king. 8 As they have done from the day I brought them up out of Egypt until this day, forsaking me and serving other gods, so they are doing to you.
1 Sam 12:17-19 : 17 Is it not wheat harvest now? I will call upon the Lord to send thunder and rain. And you will realize what an evil thing you did in the eyes of the Lord when you asked for a king." 18 Then Samuel called upon the Lord, and that same day the Lord sent thunder and rain. So all the people stood in awe of the Lord and of Samuel. 19 The people all said to Samuel, "Pray to the Lord your God for your servants so that we will not die, for we have added to all our other sins the evil of asking for a king."
I don't know what has changed such that God now needs help. :)
The idea is wholly scriptural, and we don't need to pretend some books do not exist to prove it. "As my Father has sent me, I send you".