The question How was the Basilisk so stealthy? was closed as Not Constructive. Based on the wording of the question, I don't know that I 100% agree with that, but I get the argument.
This comment from Slytherincess caught my attention though.
While this is a question that I also have wondered, it is not answerable by canon and calls for pure conjecture. I hate to VTC, but in this instance you're asking us to speculate and basically list plot holes. This is not a site for theories. This is a site for definitive answers that can be substantiated by canon. Sorry, but I feel a VTC is appropriate.
This is where things start getting fuzzy for me.
I agree that we should try to avoid speculation whenever possible, using canon to back up our answers. But does this really mean that all questions that can't be 100% answered with canon should be closed? Sometimes new material may be added to the canon, or sometimes the answer is just incredibly obscure, or sometimes there just isn't an official answer.
Consider some of the following questions which cannot currently be 100% answered via official material.
- In the Alien series, what is the meaning of the “LV” designation for planets and moons? - notable because the accepted answer is that there is no canon answer.
- Could the Enterprise beam a vampire into a house she didn’t have permission to enter?
- Why don't muggle-born wizards use Muggle technology to fight Death Eaters? - Jeff mentions vaguely remembering a quote from JKR, but no one has been able to find it.
- What was Starbuck?
- Where is the rest of Yoda's species? - another question where the accepted (and canon) answer is that there is no canon answer and may never be one.
- What is the Joker's real name?
- At what time can you start feeding Mogwai?
- How did the Zombies infection start in the Walking Dead? - possibly the granddaddy of all "there will never be an official answer" questions
I feel like automatically closing questions which either don't currently have a canon answer, or probably don't have one, may discourage users from asking questions that may actually HAVE a canon answer.
For example, I never would have expected some of these questions to actually have canon answers or answers that could be reasonably derived from canon information.