In Italy it already happens. Users comment on each other. We of italygame take care of the comments with 10% of the vote, about 10 comments per day. Of course it's not a lot to entice people to comment, but it's a small support.
If you take a look through the posts there is enough interaction. For example @lupega, @kork75, @aston.villa, @pousinha, @robytrix, @dim753, are the most active but there are many others.
However, I'm open to any experiment.😉