Some topics are perennial. Unlike some other forums that restart these topics periodically, we choose to keep the one thread alive. SMF can handle thousand-page threads, so there's no technical reason not to. No one is expected to read the whole thread -- actually, that'd not be a good idea with Random Thoughts (one that's always been a BB thread).
Also, I don't remember how long you've been here, but some of these threads predate RAF Social (and were briefly locked when Social was introduced).
I third considering some moves to Social from General. QQ might belong there, Crush is a definite, and so on.
Honestly, I mostly read from the "Unread Topics" list, so categorization doesn't matter too much to me except when I occasionally start new threads.