I think you'd be surprised on how much on a knife edge the whole process works. It's perfectly plausible that something that ends up on the front page gets only a handful of upvotes in the first twenty minutes, or half an hour. Moreover, once an article has been submitted, you're not supposed to resubmit it, and many moderators will remove duplicates.

I'm actually involved in moderating a fairly large subreddit, and we have periodic waves of neo-Nazi posters gaming the subreddit, and they are surprisingly effective at altering the general mood. You can also see some genuinely shocking opinions as top posts on r/worldnews. These are subreddits with hundreds of thousands of daily visitors. If reddit is operating a system which can easily be gamed, it matters a lot.

In this case, with enough proxy accounts, and a modicum of programming experience, you could anonymously supress stories you don't like, with some ease. Do you not think that matters?