One way this is often addressed is replacing downvote with flag, and with enough flags it gets hidden (flags and upvotes aren’t inverses of each other).
That doesn’t seem to scale well with the number of readers. Some discussions attract more people than others; so in the less popular discussions almost nothing would be flagged, but in the more popular ones, any slightly controversial comment would be flagged.
One way this is often addressed is replacing downvote with flag, and with enough flags it gets hidden (flags and upvotes aren’t inverses of each other).
That doesn’t seem to scale well with the number of readers. Some discussions attract more people than others; so in the less popular discussions almost nothing would be flagged, but in the more popular ones, any slightly controversial comment would be flagged.
You are assuming a fixed cutoff which I was not.