Then why to send pms warning us about bumping old threads.
Forward them on to an admin if you feel they aren't right. Bumping is a specific thing - where you're posting something pointless in an old thread to bring it up to the front page - that isn't acceptable.
Otherwise, the correct thread to post something is the one where it is most relevant, regardless of the age of the thread.
Obviously it's a bit of an exception with people who have stopped modding games - but we usually accept requests for download threads to be closed from people who have stopped.
In a general sense - across the entire forum I vastly prefer that threads simply fall back in the listings rather than specifically closing threads. Being an older discussion alone isn't a reason not to post.
As with anything, if you feel an old thread has been pointlessly posted in, report the post, don't reply.