Lon’s response is dead on, and I would also add this:
I’m a relatively new user here at Medium, and one of my pieces absolutely took off beyond my wildest dreams. Hundreds of comments, followers, thousands of little green hearts. It can be a bit overwhelming, especially when it all happens at once. I started out trying to respond to everything, but it was simply taking over my life. I wanted discourse, to be sure, but there was simply no way I could adequately respond to everyone. And, yes, I started to dread getting notifications of comments because some of them were just…really mean. So some of us might just be burnt out.
Being thoughtful and respectful always leaves the door open for people to explore and expound, so if you do that you’re at the very least creating an opportunity for discussion, which has value in itself.