Well, technically speaking, writing can be used for both [nearly-]ephemeral communications (letters/messages) and persistent storage (books), so literacy levels alone don't immediately imply that the knowledge is archived and distributed this way.

But your point is absolutely valid, because, I believe, every (or so) civilization that had invented writing, had books or similar concepts (tablets, etc). Persistent information storage in form of written text just can't be "western" thing. Libraries had and continue exist nearly everywhere, regardless of the culture.

I get the feeling that tsunamifury is suggesting that chat, rather than a document browser, ought to be the metaphor for the end-user Internet -- that's what "vast majority of the planet stores knowledge in people and references it via direct communications" seems to be alluding to.

Chat interfaces are certainly all the rage right now. Having a properly threaded log of your interactions with a service provider is one benefit of messaging vs. browsing; lack of exploitable UI space for distracting advertising and pointless branding is another. At the same time, the UI paradigm for chat apps isn't even yet up to '70s state of the art. It's only good for very short interactions with limited or obvious choices.

Perhaps if you reinvented the web well enough, it would become the Internet. Everything would be just some communicating components, only some of them would be graphical, for example.