FYI...there was actually strong Jewish prohibition against writing the Oral Law until well into the Christian era (200? 300?). It was supposed to be passed down orally only.
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.
Why would the Apostles and those that traveled with them write the Scriptures then?