Why is the following question off-topic?
It is worth mentioning that close reasons are displayed differently to different users. You should see this: "Closed. This question is off-topic. It is not currently accepting answers."
However, users who can cast close/reopen votes see this:
This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level.
Notice that it contains the link to this post: How to ask a good question. (This link is contained also in the version displayed to the user.)
The more detailed description says that the reason for closure was insufficient context. You can find some related posts here on meta if you browse through the questions tagged context.
Several versions of the message were introduced in August 2019, some more details can be found here: How could we improve our planned post notice improvements?