HR departments perform different tasks.

HR departments perform different tasks. They might take full responsibilities for human resource activities in some companies whereas in others they will share the role with managers. Some of the responsibilities of HR departments are: employment and recruiting, training and development, compensation, benefits, employee services, employee and community relations, personnel records, strategy planning, health and safety. The role of HR has changes and enveloped over time. It began as a purely administrative function but now …

…to interview applicants and recommend right people for right place. That task would be impassible without good understanding of what skills are necessary to perform right job. One of manager's responsibilities is to provide feedback to those whose performance needs improvement. In order to do that he needs to be able to evaluate how well each person is doing its job. Again, this requires that the manager clearly understands the task required in every job.