The doctrine of how Jesus worked is the Jewish rabbi method of working. You can see it in other peoples too, such as the guru in India. The rabbi, teacher, guru, teaches by taking on disciples who follow them around watching their actions and not just hearing their words, their sayings, but seeing how the rabbi behaves in accordance with those sayings. The note takers are the disciples, not the rabbi. The disciples write what they witness the rabbi say and do. The rabbi teaches by action, works, not just words. The words are often directed at the disciples, applying to them, not theoretical, but words requiring actions or changes of behaviour. This way of rabbinical teaching required disciples with time to devote to close contact as much as possible. The ones who had this contact become primary witnesses and authorities on the way of the rabbi as well as practitioners of that way, behaving accordingly (vitally important). It makes sense that they be the ones to write the accounts. Like a student taking notes and eventually becoming a teacher too. The gospel continued this way for decades, person to person, combining words with witnessed actions, before the emphasis turned towards written accounts and the reading of them to churches. The disciples themselves were Jesus’ document.
