I'm thinking that some of the extra stats probably are from people reading the actual comments themselves, but I guess it probably does make people read your actual stuff more too due to increased visibility(and also just since it's fun to get comments on your writing so I guess that makes people more likely to read your stuff too). Either way I haven't really been commenting enough to actually do anything except speculate so I guess this article is a good reason to start doing that and actually test it for myself