But, " It wasn't that long ago that there was no written Word available."

Really? Then consider the following:

Psalms 12:6-7

• "The words of the LORD are pure words: as silver tried in a furnace of earth, purified seven times.
• Thou shalt keep them, O LORD, thou shalt preserve them from this generation for ever."

God is all-powerful. He made the heavens and the earth and all that it is in it. Since He is powerful enough to do that, He is powerful enough to preserve His Word.

II Timothy 3:16-17

• "All scripture is given by inspiration of God and is profitable for Doctrine, for Reproof, for Correction, for Instruction in Righteousness;
• that the man of God may be thoroughly Furnished unto all good works."

The Old Testament scriptures thoroughly furnished man of that day unto all good works, and Christ continually referenced it to prove truths to Old Testament Israel. Jesus and others read and quoted scripture, never any oral traditions, except to condemn them. That's not an insignificant fact or something that is not pertinent. Likewise, when Satan himself tested Jesus, the Lord gave us our example of reproof by His steadfast reference to "the authority of scripture" to prove Satan's understanding, tempting or declarations were flawed.

Matthew 4:3-4

• "And when the tempter came to Him, he said, if you be the Son of God, command that these stones be made bread.
• But He answered and said, It is written, Man shall not live by bread alone, but by every Word that proceeds out of the mouth of God."

What proceeds out of the mouth of God is His Holy infallible word, and this was written in the scriptures as man's authority. These words are as the bread or sustenance of life, that man must live by. Consider that Christ could have answered Satan in any way that He wanted, for He is Perfect God, and an original perfect answer could have been spoken at any moment. But instead, Christ pointed to God's word that was already written in the scriptures as His reply to the adversary. i.e., that was the perfect authority where the answer would come from. This yielding to what was written in the scriptures is an example and lesson for all faithful Christians about what authority we should defer to in coming to any Biblical truth. And Christ answered this way not only in debunking un-biblical assertions, but also when He was presented with scripture that was taken out of context. When this occurred, Christ again defers to additional scripture, that would "qualify" or shed more light on the scripture in question. For example:

Matthew 4:5-11

• Then the Devil took Him up into the Holy City, and set Him on a pinnacle of the Temple,
• and said to Him, if you are the Son of God, cast yourself down; for it is written, He shall give His angels charge concerning you, and in their hands they shall bear you up, lest at any time you dash your foot against a stone.
• Jesus said to him, It is Written Again, you shall not tempt the Lord God."

In other words, Jesus replies to scripture taken out of context, with an additional scripture which "qualifies" and clarifies the scripture, not denies it. For no scripture contradicts another scripture. In doing this, Christ is demonstrating to us how we are to exegete scripture. i.e., he didn't deny the the first scripture the Devil submitted. Yes, it was true God's messengers will watch over us. But the additional scripture Christ submitted clarified how that didn't mean that we could test or tempt the Lord God. This is a perfect example of God illustrating the ultimate authority of scripture, even in the face of those who present other scriptures taken out of context. The perfect answer by Christ to combat erroneous understanding of scripture, was for Him to quote "additional Scripture" that shed more light on its true meaning. Thus we learn that the scripture is still the ultimate authoritative judgment over whatever other scriptures that anyone might misuse or misapply.

Christ Himself references the true and supreme authority declaring, "it is written!" This is a representative sample or model of the posture that we are to take in order to test the spirits to see if they are of God or of antichrist. We compare their words to "what is written," countering their Church traditions with the authority of what God has inspired written. The same can be said about any debate of any doctrine of the Church. The correct principle in faithful Hermeneutics is to always defer to a sound and ordered exegesis of scripture, and not to consensus, tradition, leaders, or the ecclesiastical body. This is precisely as Jesus demonstrated in His debates with the religious leaders of His day. He was God Himself, and yet He appealed to the authority of scripture that we might be enlightened.

Matthew 21:42

• "Jesus said unto them, did you never read in the scriptures, the Stone which the builders rejected, the same is become the head of the corner; this is the Lord's doing, and it is marvelous in our Eyes!"

They were to understand that it was written in the scriptures, the supreme authority that furnished them unto all good works. Therefore, they should have searched God's words that they would have known of the coming Christ. Likewise, when the New Testament was added, it Biblically follows this same principle of thoroughly furnishing us unto all Good works. The same principle would continue in the final Testament of God's Holy word. Once completed, the entire New Testament scriptures (like the Old Testament was) is the guidebook of truth for the Church. It is now a "completed work," not a work in progress.

http://www.mountainretreatorg.net/bible/sola_scriptura.shtml