re: "It is written..." because the rabbis, who could read, told them so. The Torah is read aloud in service.
So your story is that Jesus could write, but chose not to? So we're back to God deciding to have Jesus just mention stuff to a few people, rather than do the helpful thing and write it down?
Are the 5,000+ that Jesus talked to when he fed them bread and fish 'few'?
Yes, the Torah was read aloud in service, Isn't that why Jesus read Isaiah 61 aloud at Luke 4 vs16-20?__________