I don't see why a committee would have to be limited to some people, nor why it would not be transparent who gets involved in it, nor why a stable group would be perceived as having more conflicts of interest than a changing group.Randomly selected juries avoid the "cabal" problem -- it's transparent who gets involved, it's not limited to some people, it's not the same people all the time, and it's a bit easier to deal with (perceived/claimed/whatever) conflicts of interest.
However, there's still no example, so I may not really understand.