And even then, HN's guidelines say the downvote button is for comments that don't add to the discussion. Even a comment with incorrect information can add to the discussion (though admittedly much less often than an accurate comment), so it's not really about accuracy, either.

(But I will admit that I often downvote things simply because they are inaccurate.)

In general, that's the risk of crowdsourcing signal on anything... You get the wisdom of the crowds.

What that means depends on the crowd.