I built my presence here through commenting. I'm on 70k :) I always try to add something to the conversation. Asking questions is a great way to keep it going.
I don't actually get that many one or two word comments and it could be much worse. Another platform I used was plagued by 'Nice post' comments. What makes me laugh is when people try to tell me what my post means, e.g. 'Running is good for you'. Well duh!
I see a lot of posts that deserve more comments. There are music posts and comics that took a lot of effort to produce and they get little feedback. We need to support the sort of content that could bring in a bigger audience. I'm amazed my ramblings do so well, but then some people will just be fishing for votes :)
BTW I think the comment rewarder is a good way to give back to those who engage.