Is it true that people can't read 3 lines on Twitter?

I think I read this in a book or on some social media post. It was about how many Japanese people can't read even 3 lines on Twitter (meaning they can't read properly). I'm not sure if it was exactly 3 lines, but the gist was that people can't even read short posts like those on Twitter. What does this mean? 1. They can't read the text. 2. They can read the text but don't understand its meaning. 3. They have no intention of reading it. I assume it's one of these three, right? I think it's the second one, not understanding the meaning... When I was a kid, I read books full of text, but they were completely boring. It was because I couldn't visualize the content. It took a lot of time, and I barely understood anything. So, when it came to reading, I preferred manga (manga doesn't take much time and is intuitive). I used to watch a lot of anime and play various games, but maybe that was a reaction to not being able to comprehend text (I can enjoy novels reasonably well now). I don't know about others, but in this era where information is so abundant, I'd think more people can understand text. Or am I wrong? (Perhaps too much information actually lowers intelligence).