I always read it as being "last response" also; that is, until a couple of weeks ago. I pointed out that there was already a valid link for a program and I was told that the rule meant last valid link posted as opposed to last post. There had been discussion in this thread for a day or so after the last link was posted so technically, even though the post ended on day 2 the last valid link was posted on day 1.
I think it's all simply a matter of something we learned in kindergarten - wait your turn. I have seen so many threads fall to the wayside because people just do not want to follow the rules. The whole point of this board is to help each other get referrals, isn't it?