We have this example also.
Now these were more noble-minded than those in Thessalonica, for they received the word with great eagerness, examining the Scriptures daily to see whether these things were so. Acts 17:11 NASB
The appeal to Scripture as the ultimate source is well attested to in the Bible...both Old and New Testaments.
Your “proof” is proof only by inference (not directly stated so), which is no stronger a proof than the Church and her Papal authority presents scripturally in defining some Dogmas.
In your beloved scriptures, in fact, a particular question arose for which the Church held council (Acts of the Apostles). Out of the council came the Dogma which lives as decided to this day. Where in Scripture does it say they just looked it up in the Scriptures and found the answer right there?
They then proceeded with the answer as the future direction for the Church.
Are you supposing that God is not able to likewise provide for future questions that may arise not encountered before, which the Church, vested with God’s authority, may discover the answer to and then proceed with clear definition even if the Scriptures do not already define it, where the decision of the Church, as always does not contradict Holy Scripture?
Is God also incapable then of giving the authority of a priest to forgive sins, as inferred in the Scriptures and carried out faithfully by the Catholic Church?
Or is it only Protestants who are capable of defining Dogma by inferences found in Holy Scripture?