It looks like, at least in some sections (Seekers of Perl Wisdom), when you hit the comment link, it creates the response for you. In this Perl Monks Discussion section, I hit the comment link to make this reply, then went back and reloaded your original question. No empty reply there.

Seems like an inconsistency to me. Hitting Submit or Stumbit or whatever it's called today should be what creates a new note. (You can check this if you have the XP nodelet enabled -- when do you gain experience for adding a writeup? After you hit the reply link, or after the first time you hit submit?)