It takes both leadership and management to make a business successful. If you can find a balance in one person, even better. 

Leaders are visionaries, it seems like not everyone can be a visionary. Managers carry out that vision or create the steps in other workds.

Being a good manager is crucial to a successful workplace. We all have worked for people that made our jobs harder. We try to get away from people like that and change jobs. In that way, managers contribute to the longevity of workers as well.