A prize might be awarded to the most referenced contributions.
It may provide focus in the dialoge.
It may provide a way to attract contributiors.
It may allow to establish rules for the discussion.
It would however require separating the contributions of different users. Editing the contributions of others would probably first require citing and copying it and then publishing a modified version.
It would also require mechanisms to prevent fraud.
Users may be allowed to use aliases, but could only cite/reference with one unique identity.