Well, there's already a canned close reason that fits Lunatic Speculation:
too broad There are either too many possible answers, or good answers would be too long for this format. Please add details to
narrow the answer set or to isolate an issue that can be answered in a
The way that you find out whether or not these "edge" questions are on-topic is you watch the answers that come in. In this case, the answers are all generally of interest to programmers, and they generally stay on point. The death knell for a question like this is when you see idle, off-topic conversations break out, or multiple link-only answers, or people trying to paint the bikeshed.
That said, it is rare that I look at the answers when evaluating a question. Questions should stand on their own merit. Overall, I'd say that the one you linked is pretty good; it's well-written, shows prior research, and isn't merely a request for external resources or idle speculation.