The "catalyst" role is critical to freenode and an essential building block of channels. No one is required to be a catalyst, but the users who perform this role ensure the smooth and efficient functioning of the network.
IRC does not automatically produce a stable culture of cooperative effort. Even in cases where cooperation is intended, misunderstandings and personality incompatibilities can result in an extremely chaotic and hostile environment. Catalysts help prevent and resolve misunderstanding, calm the waters when users have difficulties dealing with each other and provide examples of constructive behavior in environments where such behavior might not otherwise be the norm.
Catalysts try to resolve problems, not through the use of authority and special privilege, but by fostering consensus, gently nudging participants in the direction of more appropriate behavior and by generally reducing the level of confrontation rather than confronting users with problems.