The hivemind doesn't agree with itself on anything, so that can't be it.
A comment is unsubstantive if it doesn't include any more information than 'boo' or 'yay'. (Although polite empty comments like congratulating someone are just fine.) On HN we want discussions where readers can learn a bit more than that someone likes mining.
Thanks for getting back to me. I have to disagree with your first point. There is very much a hivemind on HN, and any comment that doesn't fit in there gets downvoted. I find myself scrolling all the way down every thread to get different points of view, by the time I get to the interesting comments I can barely read them because you made the CSS make "unpopular" comments barely visible.
I'm currently negative 3 points for trying to start a conversation about the topic at hand. How is this not a hivemind? I followed your instructions and yet this still happens.
Edit: your comment got me thinking, what is substantive to you? Is it just the general hivemind of HN that's only allowed here?