Agreed, if anything I think submitting a pre-existing story should actually be worth more score than upvoting it. The problem lies if people give out submit links pre-loaded with the submission URL/title (if that's possible?).
But if you form a cabal to make front page of HN - whether your clique be Twitter followers or a "group of friends" on this site - it's gaming the system.
Essentially, that is what the article advocated (oh, and write interesting content - duh).
A "cabal" typically refers to a group secretly united to promote their own interests. I'm not sure that tweeting a link to a blog post meets that criteria.
A cabal of voters could easily be setup on HN. That is problematic.