Here's a question back at ya', if you are flipping through the television channels and see an episode of Law and Order, what happens if you change the channel only to find the same episode on another network channel? Should one network not show the episode due to redundancy? These threads are "threads" intertwined into one big rope of discussion where people read, comment, don't comment, interact or not interact. Some volunteer but to what extent? I would say that my taking time sitting here at 5:17 a.m. sipping java prepping for another hectic day is "volunteering" to some degree. If none of us commented then this site would be a waste of the Internet, or Internets if you're a G.W. Bush fan.
I suppose if duplicate threads are a TOS violation then, well, who knows... Have a Great Day!