Are we talking about laptops in grades advanced enough for students to waste time on Reddit, or smartphones in the hands of young children?
My contention is that it's feasible to use laptops in classrooms productively, especially considering the value in applications like word processors. Of course it's necessary to balance the educational value with the potential for distraction. A way to minimize the latter is to extend classroom management to address device use, e.g., instilling discipline. I've personally seen it done well and done poorly (often not attempted at all), and given an otherwise healthy classroom setting, it comes down to discipline and ethics that address device use. That comes after tailoring the specific device format (e.g., tablets lending themselves more to entertainment, socially and habitually) to the appropriate grade level (maturity, responsibility, and technical potential increasing with age).
Some classrooms are too disruptive for device use, but that's not inherently a tech problem, even if you blame disruptive classrooms on broader cultural problems stemming from tech's role in society. Other classrooms exist in cultures that reject the necessary classroom management strategies.
It's not my contention that any device format should be used at any grade level and that distractions can be managed by simply saying "don't" and expecting success.
To address your other point above, yes, reading a book is different, often better, than reading on a screen, even for adults, so I'm also not arguing that devices should replace books.