Each group of people, that do anything to help people, has own leaders.
"Leader" - is not only the main participant of a team, he is like a basis of team. He needs to motivates each other, always be quiet and reasonable. One person or many people in team can be leaders. But what is better?
There are many arguments for the fact that there would be only one leader on the team. In many situations, one leader can be more useful, because nobody will try to argue his decision. And always his voice will the most important for all team.
But in other situations, many leaders can be more better for team. For example, many leaders can come up with solution, that would be the best decision in this situation, because they can fix mistakes of other leaders.
I think that one leader can be more useful for the team, because his influence can strongly reduce disputes between participants and all members of the team will listen to him and without a leader will not be taken any action.