This question is about posts on askubuntu in general, but I'll use my post as an example:

How do I backup the pre-installed Windows before installing Ubuntu?

Only recently I've found out that the post has been closed for being off-topic and then later reopened.

https://askubuntu.com/posts/166934/revisions

It seems there has been some consensus between 5 moderators who decided to close it. My question is, how does a post becomes off-topic. Is there a debate I can see and maybe defend the post? Or do moderators just independently label it and if enough moderators do so it becomes off-topic?