Majority of readers are lazy on the commenting process, lol. They just want to read and read....I think it's part of human mentality...Humans love to keep getting something out of everything but not giving in return. You get what I mean. I categorized two readers in to two types...
1.) The first type is loud readers, they usually are louder with their comments on comments section. They love your story to bits and want to interact with the author and everyone. They got their fix that way.
2.) The silent type readers. They add your story in the library, they regularly read your update, then move on with their lives with out saying a single "Hello" in your comments section.
Why don't you make an experiment yourself? Try to refrain updating your story for just one week, let see if the comment section of your story will be flooded with complaints...just kidding! Take care.