Communality doesn't seem to require individuals separate or superior to the rest such as priests - or if it does, why does it?
Hold on! Red flag! Clergy aren't considered "superior" to the laity. Speaking for Xy, all ministry is, at its base, baptismal ministry. The ministry of the laity is general; the ministry of the clergy is a "called-out" ministry for a specific purpose. But both are authorized by virtue of baptism.
The clergy are called out of the membership and set apart from the laity for this specific ministry of leadership. So, no one is "higher" than anyone else.
The specific ministry of the clergy is leadership. Every community needs leadership that is at least somewhat set apart to coordinate interaction, to provide focus, to set direction, to help maintain momentum, to maintain some objectivity in order to foster perspective and to oversee group dynamics. I don't know of any community that doesn't have some semblance of set-apart or recognized leadership. In the context of the church community, there is a further, more theological purpose.
Leadership/laity is the differential vehicle by which a communal energy and a communal dynamic is created. The theological term for it is
perichoresis, or "rotation/completion of a cycle." It mirrors in the purely human setting of the church community the same dynamic we believe is present when God reaches out to us, we respond, and God works transformation in us that allows us to serve God more fully.
Since we believe that the church community reflects the community of the spiritual realm in the dynamics of its relationships, such differentiated leadership is necessary in order to reflect the relational dynamic of a God that is differentiated from God's people, and yet working in concert with God's people in this dynamic of
perichoresis.