Comment by Karrot_Kream

I think it's a bit tougher than that. On top of what zahlman said, a lot of "casuals" don't really bring much value to a social media site. If you comment once a year you're not really offering much to the conversation. That's what makes this problem so tricky. The most motivated users are usually motivated by something more than intrinsic motivation. The least motivated users just aren't very good users of the platform. A better incentive structure would help incentivize the "moderately motivated" user.