I swear, the HN front page algorithm is easily gamed, this gets a few points quickly and it rises straight to the front page. I don't know if HN is accounting for vote rings but some penalizing should be implemented.
Furthermore, there are protections against vote rings. If, for example, someone votes directly on the URL for a story, or if the referrer is often the same, those votes are discarded.
However, you're right that the algorithm has evolved over time. Visit https://news.ycombinator.com/classic to see the previous algorithm in action.