Funny thing, it looks that this question might needs more details
First. I'm still learning the workings of Super User. As an assidous participant on Meta Stack Overflow, Meta and Meta Web Applications (disclaimer, I'm a mod in that last site) I'm aware that while the platform is the same each communiy is different, but have some common circumstances.
I usually leave comments when I flag/vote to close, but I don't always do it, so when I read this title I though that it was addressed to me, due to some recent cases that I not remember if were on this site or anothe were I didn't left a comment.
While I think that might be worthy to leave comments asking for specific details I strongly disagree making leaving comments for closing flags/votes as a "obligation". Also I don't think that the lack of comment should be a reason to vote to keep a question open when it clearly should be closed as needs details / is unclear.
The Ask Question page already show a modal to new users that they should discard before be able to fill anything
Then the fields already have help, and the side panel have tips, as is mendtioned in the above modal.
Then it's asked the the user to review their question to review it before posting providing guidance about what they should review.
If they ignore all that help (rethoric question ahead) what tell us that the OP will read the comments?
P.S. The modal might be customized, i.e., to point to FAQs with guidance about the typical details required for the most common questions. Personally I think that questions about using application software should mention what was found in the official help and why it didn't meet the OP needs.
Trying to integrate stuff from the following posts:
I think that this request might eventually made more specific at least for two audiences:
- "local fandom" (active assidous Super User members that regularly flag/vote to close, having or not access to the review queues, that follow Meta / Chat)
- For this people, maybe nothing special to add, maybe adding some statistics if you find that they might help to support an idea.
- "the others" (occasional users, including no longer assidous users and users with high reputation that doesn't follow Meta / chat)
- Having a "welcome" / "welcome back" about what are the current Super User workings regarding closing questions (i.e. a list of the "must read" meta post) could be helpful to have a place to point these users.
For those who likes to thing for the long term, check out How might the Staging Ground & the new Ask Wizard work on the Stack Exchange network?