I do understand that real life is - or at least should be - more important. Kids to take to school, husbands to feed, relatives to call, friends to meet, cakes to bake, laundry to tackle, dogs to walk, museums to visit etc. Many of us might even work and/or sleep. If a writer is really productive, posts daily and gets a lot of feedback it's quite natural that it's (at least almost) impossible to answer all reviews.
But if a writer posts something let's say once a month or takes part in something like the hd_career_fair, gets some but not too many (whatever that is) reviews and doesn't even thank for them what does it tell?
Is it time for the RL card again? Or are those people just being impolite? That would be hard to believe in most cases because their other posts give the impression that those people are kind, nice and considerate. Or is the next fic taking so much time and energy that thanking for reviews is just too much?
I've always been my own worst enemy and I hate pretty much everything I write. Could that be the reason why writers don't comment? They have written the fic that was lurking in their minds, posted it feeling that everyone will hate the story and laugh at it and them. So they don't read the reviews at all? Ever?