I’ve seen it both ways. Working in a teams where the vast majority of the staff were multi-disciplined, and in teams where each section was clearly its own echo chamber to the point where it felt like the considerations of one team would always be ignored by the other. I can tell you that the former was not only infinitely more productive, but that the results were exponentially better.
Excellent post. Jack Shedd’s Big Contrarian is turning out to be a consistently great blog.