Addressed in the article (which I recognize is behind a paywall so you may not have seen it):

“But even if the backlist contains a wealth of fiction starring boys, that’s not always a help to today’s young readers. Laura Gardner, a veteran middle-school librarian in Dartmouth, Massachusetts, told me that although some of the classics still stand up—kids love Gary Paulsen’s Hatchet and its sequels, along with the I Survived series—many students have a hard time getting into literature from past decades. Thanks to the disruptions of the pandemic, middle schoolers are coming into Gardner’s library with lower reading levels than they were when she started her career 17 years ago. But even the high-achieving students, she’s noticed, can’t be coaxed into picking up a book for fun unless it’s action-packed. “If the pacing isn’t pretty quick, then you’re going to lose the kid,” Gardner said. Older titles tend to feature more descriptive language and longer chapters; they start with more exposition, and have plots that unspool more slowly than today’s attention spans are used to.”