I think one of the commonalities there is that that kind of pictorial information still shares many of the advantages of text, namely that they are searchable,

I think one of the commonalities there is that that kind of pictorial information still shares many of the advantages of text, namely that they are searchable, asynchronous, and permanent. Speech is often problematic, because it is so ephemeral, unless extra pains are taken to record it. Ideally, you'd have voice recordings or at least good minutes taken of an in-person meeting or telephone call(which actually just turns it back into text...), so that the information doesn't just disappear into fallible meat-memory. The other problem is that it is a real-time communication. You can only consume the content at a single rate - you can't speed through the filler or go back and reread something that didn't at first make sense. With recorded video or audio, you can sort of do this, but it is so slow, compared to reading speed, and it's not like you can just Ctrl-F through it