Topics are closed for a variety of reasons. Duplicate postings is one reason. A thread that has run it's course and has become stagnant is another reason. We have a timer set up in the software that will automatically close old threads if no new replies are made in them after a few months. Topics that have become contentious or violate the Terms Of Service are other examples of why we close things.
We also move topics, such as this one, to more appropriate sections. In this case, the question was asked in the Caribbean Port Chat area but asking why topics are closed has nothing to do with Caribbean ports. So I moved it here to the Lido Deck.