“how writing could not convey as much as speaking and therefore all meaningful teaching and story-telling should be done orally.”
This is why a vast majority (and still rapidly increasing) of the media people consume daily is music/photo/video, and less and less written word.
These ancient thinkers were not incorrect in the least.
Meanwhile, “book reading” has declined drastically in the last 30–40 years according to Pew Research and Gallup Polls.
However, people are likely not reading any less, with text-messages, blogs, succinct e-news sites. They are simply reading less long-form, and reading in shorter increments.