This is an excellent post. I’d like to add my perspective.
As a moderator, and with the move to the new platform, we have had to close a LOT of old threads.
So why do we close old threads? Many reasons:
The original poster hasn’t been active or even logged in for months or years.
The thread was started years ago.
The thread is so old that there isn’t any context for a new comment.
So many other reasons…
What happens is that someone does a search, find a thread, doesn’t look at the date, and adds a comment. Others don’t realize right away that it’s an old thread. Eventually, someone flags it, we are alerted, and then we close it. CC is working to resolve the issue of long-closed threads from being reopened.
Sometimes old threads are pinned because they continue to be relevant as time goes on and people keep adding useful or relevant info to them.
Some threads are closed because posts are repeatedly flagged. We will try to keep them on track. If that doesn’t work, we will close the thread.
Some threads are closed because maybe the OP has a specific and valid reason for wanting them closed. That isn’t common though.
Some threads are closed because the OP does a “hit and run” and/or is there using a duplicate account, not revealing their true identity.
Sometimes threads are closed and then reopened.
As you can see, there are many different scenarios. To address your concern of non-heated threads remaining open, many users aren’t aware that a thread did become heated and posts were flagged and deleted or edited. At some point, it becomes unmanageable. Leaving threads open when it’s a hit and run poster, or a duplicate account, isn’t ideal, especially when the original post asked a question that was long since answered.
One of the best ways to keep a thread going is for the person who posted it to respond. Provide feedback, ask questions, keep the dialogue rolling. The most productive threads tend to happen when the original poster (OP) is an active participant in the thread.
Hopefully this addresses some of your concerns.