Well, depends. If you do any kind of application which 1. Needs more than one programmer 2. The domain of the program is not the expertise of the programmers

Well, depends. If you do any kind of application which 1. Needs more than one programmer 2. The domain of the program is not the expertise of the programmers Then you need someone to talk with the domain experts. Ideally someone who can communicate well, get information and handle the upcoming problems which arises whenever different domain expertises meet. This role is called a manager, sometimes product manager. Sometimes the application is so large one person is not enough. Sometime a corporation is so disfunctional there are more managers talking than programmers doing the actual work. But in its essence it is not a useful but an essential part of building something for other people.