The article missed the most important point, which is mental flow. If you are engaged in anything complex then a certain amount of your job can only be done when you have established a good mental flow. Tracking your time closely will keep you from ever entering mental flow, and therefore blocks productivity.

Put into pg language, detailed time tracking only works for people on a manager's schedule, and not those who are makers. See http://www.paulgraham.com/makersschedule.html for an explanation of that.