Leaders or managers, this is the problem. While managers can be leaders, the reverse is not a must. In fact, these two roles are often separate. After all, modern businesses seem to prefer it this way. While leaders lead, managers manage.
On the other hand, every organization strives for success. Hence, any team wants to achieve, above and beyond. However, most often, management does not have a leadership role. In fact, management often deals with quality control and compliance. Also, they exercise control and offer accountability. Modern managers do all sorts of things, yet effective leadership seems to not be on the list.