It's interesting that Cal Newport chooses to mention GTD in his title, because what he's complaining about is stuff that David Allen has complained about, too...and, to be honest, Merlin Mann and that whole community never understood. It's not about the task lists or tickler files or whatever.
It's about being able to take complete stock of your life on a regular basis.
Everything else is based on that. You get everything captured and in one place so you can look at it and say, "Okay, is this working?" David Allen explicitly suggests similar activities for teams, and high functioning teams generally do this.
I think Newport is absolutely right about the chaos and distraction that characterizes so much white collar work today. I'm not sure how fair it is to lay it at Drucker's feet. My view from the software world is that there are twin gaps in strategy and leadership in most organizations. Strategy provides the framework in which groups deploy tactics. Leadership provides the framework in which groups adopt tactics to deploy.