I don't think you've shown how this is true.  I can imagine a very helpful and useful trust network where users add those who they want to add and remove who they want to remove and those without anyone on their trust lists are simply not participating.  How is this "utterly useless"?  It seems like an ideal system which aids those who want aid and leaves out those who want left out without creating a central point of failure for those who want to game the system.