If I remember my church history correctly...
1: Jesus dies and is resurrected.
2: Apostles are sent out.
3: Majority of what we call Scripture is written.
4: Apostles start to die, mostly from martyrdom, and so they are not available to settle theological disputes.
5: Church leaders write creeds or statements of faith in accord with apostolic teaching in order to settle theological disputes. Some of the early forms of these creeds can be found in the epistles, especially in 1 Corinthians.
6: The canon of the New Testament starts to be formed. The Pauline epistles are already being circulated together, but there are requirements for any other additions. A: They must be written by an apostle or a companion of an apostle. B: They must be truthful, and this is where the Creeds come in. Because the creeds were simple statements of faith, any epistle or gospel that contradicted them could be easily dismissed.
7: So it goes that Jesus teaches Apostles, Apostles (and companions) write Scripture, Church uses Scripture and apostolic teaching to write Creeds, then Creeds are used to authenticate Scripture. The Creeds are also accepted as accurate confessions of the Christian faith.
8: But because the Creeds are drawn from Scripture, which is drawn from the teaching of the Apostles, which is drawn from the teaching of Jesus, it is Scripture that predominates. The only places that traditions show up are in the Creeds, and even then the Creeds are drawn from Scripture and subservient to the Word of God.
9: Scripture, therefore, is the norm of our faith because it is the accurately preserved teaching of the Apostles—and the teaching of Jesus, and anything that contradicts Scripture (which in turn contradicts Jesus and the Apostles) must be thrown out. And that unfortunately includes a whole MESS of Roman traditions.
tl;dr: Roman traditions have no evidence for coming from the Apostles and Jesus other than Roman Catholic because-I-said-so, whereas Holy Scripture has plenty of evidence of coming from the Apostles and Jesus. So we should be paying attention to what the Apostles themselves actually wrote before anything else.