> I was somewhat surprised to find out that illiteracy does not mean that someone needs to be a total (or near) analphabet - but rather that it is a broad and wide spectrum.
It's a very recent redefinition, pushed by people looking to make money from a panic. They're trying to make people who are simply incurious (through stupidity, fear, boredom or whatever) into illiterates. More people are literate than ever before because of the internet. Before the internet, there were an enormous number (up to a quarter of the US population) of actual illiterates.
The new definition of illiteracy is (manipulatively) somehow including people who wouldn't be able to understand something that is being read to them.
I suspect that a lot of middle-class people are illiteracy truthers, because they've never met someone who actually couldn't read. I'm from poor, black, uneducated, working people, and before the internet there were plenty who simply couldn't read. If you asked them to write the word "STOP" they would make a good attempt to copy what they remembered from a stop sign, and draw it like a picture. They're normal people, though, and if you didn't know them well, the strategies that they've developed over a lifetime would keep you from noticing.
It's going to be back again - technology has removed the need to read and write because of voice recognition and interfaces. We're calling it too early.
> It makes me wonder if literate people can regress to illiterate, for no other reason than lack of reading maintenance.
I think it's too easy to be exposed to words. To fall into illiteracy through atrophy would be like forgetting Spanish while living in Mexico. The good thing about comprehension-type skills is that they put you into a virtuous circle passively. Once your French gets to a certain point, it takes an effort not to understand French; and every piece of French you fail to fail to understand makes you better at understanding French. If you're in Paris, riding the bus, and somebody is babbling into a cellphone, you'll wish you didn't understand French.
English (like French) is just an absurdly hard language to read and write. Of course there are people who can't, at all. French, although absurd, is probably easier to read than English (though a bit harder to write.)