I think the concept of "functional illiteracy" is key. Almost everybody we interact with these days (aside from small children) is technically literate. That is

I think the concept of "functional illiteracy" is key. Almost everybody we interact with these days (aside from small children) is technically literate. That is, they can be given words on a page and read them aloud, or they can hear spoken words and write them down. This is especially true online, where this is still pretty much a basic requirement for participating in discussions. Which it turns out is not the same thing as being given words on a page and understanding them, or turning thoughts into words which convey those thoughts to the reader. That is a substantially rarer skill, especially for anything with any complexity.