This works fine if you are tackling a problem that can be sufficiently addressed by 4 developers. Depending on the size and scale of the problem you are trying to suggest and the time line required for delivery you may need a larger team.

When you begin to take that into account you realize you have to find ways for the larger team to work together and still produce a quality product. Hence the techniques being used by the author and other companies out there trying to address similar problems.