A movement built around one central leader speaks with one clear voice, but every link runs through that person. A movement of many local groups, each with its own leaders, is harder to keep on one message, but no single person holds it together. Move the movement from one central leader to many local groups and watch how the links change.
The SCLC under Martin Luther King Jr. was organised as a hierarchy, with moral authority flowing from one well-known leader. It was good at a single public message, a clear spokesperson for the press, and large actions such as the 1963 March on Washington, a joint effort by many civil rights groups in which King and the SCLC played a leading public part. But that structure put a lot on one person: after King was assassinated in 1968, the SCLC struggled to keep its momentum. Its strength was a clear strategy and leaders that governments and the press could deal with; its cost was dependence on a handful of figures, with no easy successor.
One central leader gives a clear voice but is a weak point: if that leader is jailed or killed, the movement can stall. With many local leaders, the movement is harder to coordinate but can carry on, because no single person holds it together.