However it's an unspoken rule when it comes to the Anime Discussion section that we'd prefer everybody to become necromancers rather than starting a new topic.
Then it needs to be translated into a spoken rule, and the warning on necro posts removed.
Also it wasn't always this way. It used to be a nono to necro posts, so things aren't consistent either.
I joined Boxtorrents in 2004 to download stuff. Then begun to communicate more on the forums around 2007-2008ish. The rules since the date I started using the forums never changed even when Boxtorrents switched to BakaBT.
Also, if you think about it, it's better to put everything under one roof rather than spread them out across new threads, even if they're simple questions, comments or concerns or anything like that. Unless if the type of series is different (season 1, season 2, OVA/OAD, movies) and the previous thread has no concrete discussion about them then yea you can make a new thread. Try and look over Toradora for example, it's a mess. Now go and look for Hyouka, Hanasaku Iroha or Macross Frontier. Not much of a mess, is it?
I do agree to the fact that the warning sign needs to be removed. I don't know how easy or hard it is to do so.