There are a number of reasons why a centralized staffing function would be better than letting various department heads do their own staffing. Let us look at a few of these reasons.
First, we can say that having a centralized staffing function allows the people who carry out that function to be specialists who are really good at what they do. The managers of the various units have to be good at a variety of things. They are, as it were, jacks of all trades. This might make it harder for them to be good at staffing. By having a centralized process, you allow experts to do the work of staffing. Experts are much less likely to make serious mistakes as they do things like hiring, promoting, and firing.
Second, centralization allows the upper management of the company to have more control of the process. If each unit manager does his or her own staffing, it will be harder to implement firm-wide directives or strategies. A centralized staffing department allows the upper management to have more direct control over the staffing function.
Finally, it is possible that unit managers do not have the power to do a really good job of staffing. This is particularly true when it comes to grooming candidates for higher-level positions. People who might become high executives probably need to work in various different departments so as to be exposed to all aspects of the firm’s work. A centralized staffing department can make this happen while individual unit managers might not have the clout to move these people from department to department.
Thus, there are clearly reasons why one might say that it is better to centralize the staffing process.