There is silence about a lot of things in early Christianity. There is silence about the decision to use the codex instead of the scroll, which often distinguishes Jewish and Christian texts. There is silence about the reason for the universal use of nomina sacra, and when it started, which is also a distinguishing mark of Christian texts.
One of the prime reasons to believe that the NT contained God's name in either Greek or Hebrew form is that we know that the Septuagint, the Greek translation of the Hebrew scriptures which the early Christians used, contained God's name in either Greek or Hebrew form, and that this was replaced by the Greek form of "Lord" sometime after the first century. In other words, every manuscript of the LXX that we have prior to the second century which include verses containing the tetragrammaton in Hebrew, also have God's name in the Greek text. Yet from the second century onwards this has been replaced in all copies of the LXX by the Greek form of the word "Lord". But we have no record of any discussion that this dramatic change should take place across all copies of the LXX. But we know it did. This was without doubt a "Christian" decision as by this time the Jews had resorted to other Greek translations as the LXX had effectively been hijacked by the Christians for exegetical purposes. It seems likely that whoever was responsible for the decision to change all copies of the LXX in this respect was also responsible for changes made to Christian writings.