And why would that have been??? because the Oral Law of the rabbis was less important and subservient to the Written Law of Moses and the Prophets, according to the first principle of those traditions that grew out of the Law of Moses.
It was written down later as you say when they needed it to overrule and take precedence over the Scriptures which testified against them. The Church East and West has done the same. They have committed the same offense as the Jews by elevating the Oral over the Written. It has fallen into the same trap.
Remember what Jesus said: You cannot serve two masters, You will hate the one and love the other. I hear it said that Tradition and Scripture are co-equal masters in the RCC et al, and yet this post demonstrates the truth of what Jesus said: religious people who love their Tradition but hate the Scriptures. Wake up.
Read the Scriptures: Only those with their names written in the Lamb's Book of Life will enter the Kingdom of Heaven --- not orally but written.
Again, there is no antagonism between the Scriptures and Tradition. The oral tradition of the Apostles is what went into writing the Scripture in the first place. Scripture IS tradition that was written down. And later written tradition *always* kept the Scriptures in mind.
Lemme give you an example which you may better relate to. Wednesday night Bible Study. Definitely no such animal in the Scripture. Is it a "tradition of men". Of course! But does it nullify the Scriptures? Absolutely not!
Now you may think that our Tradition is different. But I look through the writings of the post-Apostolic Fathers...I look at Polycarp and Ignatius and Irenaeus and the Didache and I can see it all the way back to the time when the Apostles walked the earth. Nobody objected then...why all the objection now?