How old is a thread when it becomes aged out and closed to replies? I can see if it's ancient, but some threads are closed with less than six months' activity. That is not an irrelevant topic.
Often in the forum, multiple new threads are started for existing topics. We deal with that. Sometimes/sometimes not, threads are combined via moderation. If automation closes threads, that's a horse of a different color. Research and/or points of reference is time consuming when multiple threads have to be opened.