Same here - I view commenting on fic as a one-time response to the fic itself, and don't necessarily expect a reply back (in fact, in a lot of forums for posting fic, like ff.net back in the days before the "reply to reviews" function, there's no way to respond to reader reviews on a fic unless it's a WiP where you can thank eviewers in the next chapter, and there's still no way for ff.net posters to reply to reviews from people who don't have an account), whereas I view a comment on meta as joining a conversation.