My line of thinking has been that if votes are used to sort comments, then there is an advantage to them be sorted by only a positive signal rather than both positive and negative signals. It's just a hunch, but my hypothesis is that enabling an instant negative response biases the atmosphere towards a less-civil type of interaction. b_b is right that Hubski hasn't been put to the test of scale that a site like Reddit has. However, its my hope that the follow/share type of propogation enhances the famliarity that users have with those that share similar interests. Hopefully this breeds more civility too.
I think the more important aspect of hubski is the block function. If I find out someone is posting really banal shit I'm just going to remove them from my feed. Since, if I read your update correctly, totally removes them from existence for me, its a very effective way of me never having to worry about this sort of banal shit. If they share an interesting link, its not like someone else I follow won't send me it anyway.
I "ignored" a user this morning that seemed to be "spamming". Now none of their posts will make my feed. If you click under "tools" you will see a script that forwardslash created so that the comments of people you ignore will also not show up for you. here is the link