Walk into almost any company and ask a random employee what they do. You'll likely get very specific answers. "I'm in marketing", or "I'm a manufacturing supervisor", or "I'm a software developer." They are all very clean, neat, and tidy, with little to no overlap.
Does this make sense? I would say that when there is a problem in the product development process, it is usually because there is a problem with translation. By this I mean, how does someone within the company translate what they are doing to success in the market? Companies spend a lot of time and money trying to integrate the disparate functions within the organization. They focus on smoother hand-offs from one group to the next. They focus on more integrated processes to bring everyone's interests to bear on the task at hand.
My question is, how often is the task at hand defined as a real market issue that needs to be solved? Sales people are rewarded for pushing more stuff into the market, and some marketing people are rewarded to the extent that they contribute to this effort. But how often are the engineers, software developers, and finance people rewarded based on an external measure? How completely did the marketing person uncover and define a true underlying need in the market? How well did an engineer or software developer do in coming up with a unique solution for that need?
Rather than focusing on pushing people together to try to integrate their competing interests, it may be better to pose a common challenge for the group to solve. If this common challenge focused on an external issue, then focusing on the competing interests of different internal functions would be less relevant. The group would naturally be pulled together, and the overlaps between their disciplines would be covered.
Now, how many companies actually reward their people for meeting these types of challenges? My guess is that there is a lot of talking about cross-disciplinary functions, but the rewards focus on single discipline metrics. This even plays out in recruiting. There is a time and place when you need strong functional expertise, and an equally important time and place when you need cross functional ability. The right people for these challenges may not be one and the same. Remember, there are people who live in the overlaps. The challenge lies presenting the right challenges to the right people at the right time. Easier said than done, but that's no excuse not to try. How are the overlaps covered in your company?