"While there are many opinions and resources on how to best regulate overstimulation and overcome digital addictions, Newport’s directive is refreshingly simple: get rid of those things that are overstimulating you."
Really what this is saying is that there are many opinions and resources backed by research and psychological study that has complicated answers. And that Newport's solution is so simple is that it almost equates to "feeling depressed? Don't!"
So yeah, while Newport has interesting ideas and can boil things down for us techies to get behind (sometimes), he doesn't fully know what he's talking about. He's not really a trained psychologist and clearly doesn't understand things at a deep level. He's basically talking to people that are like him rather than people at large.