Depends on the post. Some users focus only on posting and thus don't comment, which I think is sad.
Some users have typically quite many comments on their posts, but it's more common if the poster usually replies in the comments, generating conversations. If the poster never replies, people may lose interest in commenting.
Indeed, that's what I was thinking about that too...
Some people just post and post and post, but don't care about the discussion, I just like discussion, but hé, that's just me...