The problem I see with the viewpoint that Scripture is the "product" of Tradition is that anyone can come along and claim all manner of things were traditionally held or taught and expect that they must also be accepted as equal to Scripture in authority. Another problem with that viewpoint is that much of inspired Scripture is revelation, meaning it was not known or held by anyone before it was revealed by the prophets of the Lord and written down. When the Apostle Paul wrote of the revelation he received directly from Jesus Christ, he communicated those newly revealed truths to the churches by epistles written by his own hand or dictated to others writing for him. These were then copied and distributed throughout the Christian communities.
Paul admonished the Colossians, for example, in Colossians 4:16, "And when this epistle is read among you, cause that it be read also in the church of the Laodiceans; and that ye likewise read the epistle from Laodicea." He told the Thessalonians, "I charge you by the Lord that this epistle be read unto all the holy brethren." (I Thess. 5:27) and "Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle." (II Thess. 2:15) and also, "And if any man obey not our word by this epistle, note that man, and have no company with him, that he may be ashamed." (II Thess. 3:14)
St. Peter, also wrote in his epistle, "This second epistle, beloved, I now write unto you; in both which I stir up your pure minds by way of remembrance: That ye may be mindful of the words which were spoken before by the holy prophets, and of the commandment of us the apostles of the Lord and Saviour". Just as their example of the Old Testament called the "Law and the Prophets" was written down, so they also followed to ensure that the truths revealed to them through the Holy Spirit were perpetuated in the faith until this very day. Just as the writers of the books included in the Old Testament were inspired by God and guided by Him, so also do the writers of those books that make up the New Testament and the collection of those sacred writings we call The Holy Bible is one of the greatest gifts we have from God. Orally communicated "traditions" are far too dependent on fallible humans and, unless they are provable by the Bible, are not auhoritative for a Christian.
And the bulk of Scripture was established as such without a perpetual assuredly infallible magisterium, and souls could also have Scriptural assurance of truth.
As see http://www.freerepublic.com/focus/religion/2877917/posts?page=20#20