How are questions to be closed?
Flagging seems mandatory to me - it's important we can flag abusive or otherwise damaging content.
What about content that simply isn't suitable, is lacking in thought or detail or for some other reason will not contribute to the overall goal of achieving a good Q&A resource?
Please post answers with your suggestions.
I would not be in a rush to implement question closing here, just because that's how SE works.
If a question is a poor fit for the site, in the worst case it will be ignored, which is arguably a worse fate than being deleted. Otherwise, people will use chat to guide the author to improve their post.
It seems to me that chat (or being ignored) is just as likely to produce the desired outcome of an improving edit as closing (putting "on hold") would be. Probably more so.
We might need a proper process to *delete* unsuitable posts at some stage, but I don't think we can make that call yet, and there are other feature priorities.
The main advantage of closing on SE is that it can eventually qualify a question for automatic deletion. Closing an answered question is less likely to lead to that outcome. In many cases, all closing does is preserve the content in a state that means better answers cannot be added. It also often leads to answer material being posted in comments.