It's very likely what you did made ranking a correlative rather than causative effect. Most of these comments were probably no-follow, and even if not, devalued b/c below the fold - reasoning: the Reasonable Surfer patent -http://www.seobythesea.com/2010/05/googles-reasonable-surfer...
I agree that this can be helpful, but the way it is framed in this article is dangerous, because it can easily be misinterpreted.