It has but I'm not sure this works at the scale HN operates at now. When the community was smaller, the band of opinion was narrower, so the downvote worked better. Now that the community is large I'm not sure if this scales well. Just a thought I've had over the last few years.

Wouldn't that only be true if the vote thresholds are absolute? If the impact of a vote is adjusted based on voters present, it should scale.