There is a sybil attack possible. A user, or multiple users, could post a dissenting comment at the same children level of a post and then users could upvote all of those yielding a situation that more negatively impacts a post than just a single downvote.

Also, what happens if someone creates a dissenting comment on a dissenting comment? How does this algorithm apply? Since there is a nesting limitation, the commentator who is at the last child level can 'win'.

Interesting idea, however.