One of the areas that is sometimes hard for people to grasp in agile development in the role of management and leadership.
In scrum, teams are meant to be self managed and self organizing. If an organization can foster this, then it gains the ability to scale, and scale big. If a team can drive itself to come up with ways to improve, establish methods and conventions that are predictable and repeatable, respond to and award good practice and behavior, discipline bad behavior and communicate status consistently to internal team members and stakeholders, then the team is doing pretty much everything that a manager would do.
Essentially the team is telling itself 'what' it needs to do and 'how' the best way to accomplish this would be.
I once heard that good management in forestry is picking the right size trees, taking good care of the equipment, cleaning up after yourself and not letting yourself get too tired. Leadership in forestry is climbing up the tallest tree, looking around and yelling down to everyone "wrong forest!! we need to be over there!"
Leaders on teams guide the team to what they should be and where they should go, not necessarily how they should go about getting there.