When I have made a contribution I am interested enough in how other people are commenting to take a look later at the thread, whether or not there is a direct reply to my latest comment. If there is, I may respond to the reply. If not, there is usually another relevant post, or more, to read.
If you don't return to see how the conversation is going without any notification, perhaps you are just not that interested in the rest of the discussion, just your own corner of it?