I have to stand with Browning460 on this thread. I have responded to OLD threads to occasionally find the items still available. That can sometimes mean a great deal — especially with sellers that don't have time to keep dealing with the bumps, edits, and reposting that is sometimes needed to sell an item.
I have also found most listings more than 6-months old were dead, even if not marked as such.
I have also sold items that were posted long ago & that I stopped pushing. A reply to old posts got that started.
Any post that isn't marked closed, locked, or sold is fair game. If there is a complaint to be made it should be directed towards posters who don't mark their closed listings as such.