Commenting on stories can be a difficult one. As someone who has written for years, often without any commentary positive or negative, I do understand what you mean. However, I've also had a number of people tell me via private message that they enjoy what I write.
It can often be a fine balance between taking the time to write a comment that you enjoyed the story versus handling 15 or 20 comments raving about how good the story is an pushing for more before you'd even had a chance to turn around, usually from people who have never attempted to write a story themselves, or who think they "can't".
I have to admit I'm quite the opposite: I sometimes find too many comments a little oppressive (perhaps because I'm used to it), and I tend to start rushing, which means I lose interest in the story that way because I don't allow it time to develop. Equally, there is nothing as deflating as seeing the "new post" marker next to a story you've enjoyed, hoping for a new part, and finding it to just be half a dozen responses that barely make a paragraph between them.
I guess it's very much a case of each to our own!