I wrote a comment on this question and after a while it has been removed.
There is a 1% chance of accidental deletion of that comment by me. Other than that it should have been deleted by someone with sufficient access.
Before completing my complain, I'll first explain the story. Sasho raised one question and one answer on his first comment: he was not sure why a particular part of some paper is correct and he was thinking that paper answers the question. Then I spent time to look at that paper and first I explained why that part is correct then asked why Sasho thinks that answers the question. Then Sasho understand his mistake and I don't know why, he or someone else removed his comment and then he answered me. Then I just upvoted his comment to say I'm agree with you.
When I looked back at the question, I've noticed my comment has been removed. I think I didn't do that, unless unexpectedly I pressed the delete button. I'm wondering why someone should flag that comment or remove it?
I personally do not delete my own comments when someone provides a constructive answer to me, because, that answer might be helpful for others in the future. However, even if someone removes his own comment why should a constructive answer to that comment be deleted?
In the aforementioned case, even if after deletion of the first comment, someone doesn't understand what I'm answering, could ask it in a new comment.