(Comment link; it was not auto-deleted as suggested in a comment)
Notice the color of the username's background. It is the question asker. When closing own question, the new auto-comment does not make sense.
It is unrelated to New duplicate automatic comment makes literally zero sense when voting to close as a duplicate of an unanswered question, which is about unanswered questions.
In my humble opinion, the older "possible duplicate" served as a notice that worked regardless of who posted it.
On a related note: Community ♦ still being shown as a voter in this case can be confusing to new users who just got the close rep.