A great example of how the early churches operated is in Acts. The council in Jerusalem reveals that decision making was done as a group and no one person made authoritative decisions on their own, a presbyterian system. IOW, a sacerdotal order is unknown, it was the process of declaring an episcopal ordination that established the distinction between the laity and differing levels of clergy. Until this happened a "bishop" was an elder who had no special authority other than to conduct the service.
The development of "Metropolitans" is what really accelerated the process, until then the presbyters and bishops were viewed as equals. A metropolitan was a bishop who was appointed to preside at a meeting involving a group of churches where there was a theological issue. What happened was the "metropolitans" took their titles home with them and claimed superior authority. Over time the episcopal order was established and a system where the clergy assumed the role of the Holy Spirit of maintaining the people in their relations with God was formalized.
Yes, this is the piece I didn't understand. Thanks very much.