As an author who's also used both sites I prefer AO3's way of doing it. I hate getting Anonymous reviews to my FF.Net fics with things I want to reply to because I can't reply. And while no one can see my replies to logged in reviews, everyone can see the review - and I've had a review or too that wasn't very nice or was borderline rude but in subsequent PMs, we resolved the issue that caused the review (once someone not noticing the fic they reviewed was 4 years old). While it's never happened, I'd hate for someone to be hounded for a negative review solved in private conversation.
I think avoiding fluffed comment count making fics more visible than others is why we can only kudo once on AO3 (and why I sort by kudo on AO3 and Favourites on FF.Net). It's the fairer system. Also I've noticed that fics with lots and lots of comments often don't have the author reply to each one - it seems once you hit a certain number of comments, it stops being practical. So it has no effect on the most visible of fics?
Personally I try to reply to every comment I get, even if it's only a (much delayed) thank you. But I would understand if someone didn't reply to my comment but did to another's, if they had something to say to that other comment.
Re: 'Fluffing' your comment count
I think avoiding fluffed comment count making fics more visible than others is why we can only kudo once on AO3 (and why I sort by kudo on AO3 and Favourites on FF.Net). It's the fairer system. Also I've noticed that fics with lots and lots of comments often don't have the author reply to each one - it seems once you hit a certain number of comments, it stops being practical. So it has no effect on the most visible of fics?
Personally I try to reply to every comment I get, even if it's only a (much delayed) thank you. But I would understand if someone didn't reply to my comment but did to another's, if they had something to say to that other comment.