I'd left a "lead by example" comment addressed to the user who wrote an extended comment about why they'd chosen to immediately close What would happen if a Sun-like star were to consume a Jupiter-like planet? rather than ask for clarification or propose an edit, and a comment to another user who suggests the question "falls under the hypothetical scenarios rule". (There is no such "rule", we only have suggested guidelines for on-topic-ness which is subjective and needs to be addressed on a case-by-case basis)
As I see it, on a site with a low question rate, there's no benefit at all to insta-closing a good question that simply needs a bit of work. "Leading by example" means showing a new user, posting their first question, the best way to improve it by making an edit. Having an example is likely much easier for a new Stack Exchange user to understand than to simply close and point to help.
Yes, that was the old way, but it's far less welcoming than being helpful.
Question: Why was my comment deleted, and this this replacement comment okay?
My new comment is
I've voted to leave this question open. Rather than voting to close, I've made an edit to improve the question. Closing would have blocked anyone from answering further. There were 4 vtc votes; one more vote would have instantly blocked this excellent, thorough and authoritative answer from being posted!
Luckily at least one of the vtc were retracted, possibly in response to my two (now deleted) requests for vtc retraction. This likely facilitated @RobJeffries opportunity to post the answer.
I'm pretty sure my way is better in these cases (helpful comments and exemplary edits versus insta-closing) and I think facilitating the linked answer is evidence of this, so I'm interested to understand what was delete-worthy in my comment, and how could I have composed it differently to encourage keeping good questions open.