Not at all, "books" could also specify "long form writing". When I say I read a book, I don't specify "e-book", I just say, "finally finished Project Hail Mary".
Do you read books on phone? There you have your answer.
I am also assuming you are not a child from 3rd or 6th grade, so not exactly sure how is your comment relevant to study about kids with phones. Somehow I would think adult HN reader will have better self-control over video/game usage than 3rd/6th grader.