While I agree that a new thread shouldn't be opened when there is an inactive but fairly recent thread dealing with the same topic.
But I don't think that a topic should be rejected simply because it is something that has been seen before, even a million times before. If it has been long enough in the past since it was discussed, then it is quite possible that some of the new members (and lurkers) have not really discussed it in depth. Considering that we will all see these same arguments again in real life (I know I have), it might be useful for some people to see what the arguments really are. And reading (and perhaps participating in) a current discussion is certainly more interesting than reading an old one.
I certainly agree when the admins ask someone to think a little more about their proposal if they are posting a PRATT, but I think that allowing it to be discussed openly is more effective than simply saying its been discussed to death and moving on.