I actually thought that was what this was about when I clicked the link. And I actually agree with that result - while the lines of communication grow by n(n - 1) as you add more people, and in general this leads to diminishing returns in productivity when you add more and more people to a project, from personal experience I can say that the communication added by the jump from 1 -> 2 actually helps you clarify your thoughts and goals, and the companionship and social accountability helps you stay motivated and avoid procrastination, leading to a net gain in productivity.