I can think of a lot of situations in which Presbyteries have done superb work. And I have known many colleagues in congregational polities who have been horribly treated by congregations and who have nowhere to turn for support because the nature of the polity doesn't facilitate even collegial relationships.
Fair enough. The Baptist pastors I've had as leaders have each had other pastors as friends. I have witnessed and heard stories of Presbyteries being truly nasty to ministers though. In the case I was actually present to witness, the Presbytery swooped in to oust a minister from his congregation. Their doing so was really both brutal and sad.