Seems like the Jews started to take writing things down seriously just about the time Matthew (former Jew), Mark (former Jew), and Luke and did. So this is evidence that passing information along by writing in that non literary society was the exception rather than the rule.
Form Wiki on the Talmud:
Originally, Jewish scholarship was oral. Rabbis expounded and debated the law (the written law expressed in the Hebrew Bible) and discussed the Tanakh
without the benefit of written works (other than the Biblical books themselves), though some may have made private notes (megillot setarim), for example of court decisions. This situation changed drastically, however, mainly as the result of the destruction of the Jewish commonwealth in the year 70 CE and the consequent upheaval of Jewish social and legal norms. As the Rabbis were required to face a new reality—mainly Judaism without a Temple (to serve as the center of teaching and study) and Judea without autonomy—there was a flurry of legal discourse
and the old system of oral scholarship could not be maintained. It is during this period that Rabbinic discourse began to be recorded in writing.[1]
http://en.wikipedia.org/wiki/Talmud
Here is an interesting article by Rabbi Aryeh Kaplan in which the title pretty much says it all:
Title: "In many respects, the Oral Torah is more important than the Written Torah":
"The Written Torah cannot be understood without the oral tradition. Hence, if anything,
the Oral Torah is the more important of the two.
Since the Written Torah appears largely defective unless supplemented by the oral tradition, a denial of the Oral Torah necessarily leads to the denial of the divine origin of the written text as well…
The Oral Torah was originally meant to be transmitted by word of mouth. It was transmitted from master to student in such a manner that if the student had any question, he would be able to ask,
and thus avoid ambiguity. A written text, on the other hand, no matter how perfect, is always subject to misinterpretation.
http://www.aish.com/jl/kc/48943186.html