Based on my experience from other forums, this is usually to stop idiots from flooding the first (and sometimes subsequent, if they're persistent) pages on a forum with old news, trying to cause a bit of chaos on the site and making it nearly impossible for members to find legitimately current threads.

For example, someone could potentially drag up multiple threads on the same topic like "NEW ALBUM OUT ON XX/XX" or "NEW PRINCE WEBSITE" etc..., to make people think that it had just happened.

Done 'properly', it can become a nightmare for mods, particularly if it starts happening regularly (which is exactly what happened on another forum I used to participate in, before it just got ridiculous, because every second thread was two or three years old).

The worst abuse of it that I've seen was when it became a game; ie. pick a topic (eg. girlfriends, litigation, twitter/website rumours), and whomever can keep the most "bumps" on the front page for an hour wins, etc...

Obviously there are other moderation techniques to deal with that sort of nonsense, but perhaps it was decided that expiring the threads would stop most of it before it could start.

Annoying in some ways, understandable in others, imo.

Chiquetet said:

Based on my experience from other forums, this is usually to stop idiots from flooding the first (and sometimes subsequent, if they're persistent) pages on a forum with old news, trying to cause a bit of chaos on the site and making it nearly impossible for members to find legitimately current threads.

Yep, that would be why.

It would be nice if mods had the power to re-open a thread tho, especially since some of the mods here sometimes lock and re-direct threads without first checking to see if the thread they're redirecting people to is even open.