We rarely close threads; though the initial question may be answered, it's always possible that someone will have additional thoughts on the topic later one, or will use the thread to ask a related question. Until then, the thread may drop way down on the list if it is no longer of current interest to any members.
If someone is desirous of having a thread closed, there are several ways to accomplish that:
1. Flaming.
2. Chat.
3. Individual introduction (Those get closed and deleted routinely.)
There - this is a prime example! I'm answering not the original question, but another one...
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'Mercy!' cried Gandalf. 'If the giving of information is to be the cure of your inquisitiveness, I shall spend all the rest of my days in answering you. What more do you want to know?' 'The whole history of Middle-earth..
.'