Everything Old Is New Again
As for the technicalities, Sphennings hit the nail on the head with an appeal to "current site policy". Enough community members considered your query to be off topic that they closed it. The problem with the policies of any corporate group, such as ours, is that they are all subject to the interpretation and implementation of the individual.
And as you know, your query has been reopened. And again, this is all a matter of "site policy". Five people thought your question was off topic and closed; five other people thought your question was on topic and reopened it.
The answer to your query is quite simply: This is how Stack Exchange works. This community exists as a varied and polydimensional aggregation of individuals. When all the right people are in the right place at the right time and looking at the right question with the right attitude, the result is that they apply WB.SE policies in a way that results in your question being closed. And then, when the right other people are in the right place at the right time, the result is that they apply those same WB.SE policies in a way that results in your question being reopened.
Policies are not black letter law and users are not robots responding to programming. Sometimes this kind of situation can seem non-sensical! How can a community work when 10 people look at the same data and come to two diametrically opposed conclusions?
But this is exactly the point of SE! The community of interested experts (in our case, experts in worldbuilding) determines the usefulness of your question. They also determine what the rules are, how to apply them, when not to apply them and when it might be best to ignore that we even have rules.
As to why your question was reopened, it is clearly "a worldbuilding question" as it focuses on a fictional world or setting, requires some knowledge of the underlying reality in order to answer well; it's not a matter of narrativity or storybuilding or character development; it's not opinion based and not open ended. Your question might be old, but it has one strikingly modern feature, and that is the list of conditions that a good answer would have to address; these conditions limit the opinions and turn this into a relatively short list of things (rather than an infinite list of things). This is not a mere fishing expedition, but is a pretty well written question that has, obviously, withstood the test of time and the vagaries of policy!