If the Sierra Club had the same impact as a national government's environmental agency, there would probably be lobbyists for the Sierra Club too, and cushy jobs for ex-administrators.
Unlike a centralized agency if the Sierra Club fell to that sort of behavior its membership base would move on to other groups.
A response essay written by Eliezer Yudkowsky posted at Cato Unbound for the issue Brain, Belief, and Politics:
Is That Your True Rejection? by Eliezer Yudkowsky
The lead essay has been written by Michael Shermer:
Liberty and Science by Michael Shermer