Prior to the internet, books were the only way humans consumed large amounts of textual information. Now, we have web pages, which 89% of people use, whereas books, which have never been more accessible, still linger at 76% usage.
One assumes of the 89% of people who use the Internet, 100% of them use web browsers, web sites, and thus read lots of textual information. That's as close to 100% penetration for a technology as you're gonna get, in my view. I wonder what percentage of Americans use toothbrushes!
I suppose there might be some subset of Internet users who exclusively use YouTube/Netflix (children, maybe?) That would be the only wrinkle in the comparison, IMO.
I don't think that follows. If you use Instagram, YouTube, Imgur, 9GAG, and such, you barely need to read any text. Same for Facebook, depending on the people you follow.
I am sure you mean newspapers and magazines. Books still are.