Hacker News Reader

If this fact began in the last decade, I'd agree with you, but the linked Scholastic report shows this phenomenon pre-dates phones. Interest in reading at different ages has held steady dating back to at least 2010. 2010 is before most kids had their own smartphone. It also isn't like all kids suddenly get a smartphone at age 9.

Isn't Hacker News reading, but just not novels?

Isn't HN mainly text? Aren't you reading?

Reading, writing, discovering, voting, and convincing myself that in just one more minute I will return to my day.

Sort of. I think and exchange ideas, but I also scavenge mindlessly. I skim the comments, content myself with headlines. It's a far departure from sitting down with a single topic for a while.