If your comment won't contribute the conversation (in an intellectual sense) don't post it. Some people do post useless comments but generally they are voted down; also, the standard is not the worst comments.
Shouldn't we be aiming for positivity => upvote, negativity => downvote, neutrality => no vote?
It's not; that's all I can say. I've gotten plenty of them. Note that nobody else knows the score of your comment unless it's < 1.
> why would I get the same treatment as someone who contributes negatively
FWIW, comments that don't contribute do have a negative impact. They encourage more of the same, reducing signal-to-noise. The behavior spreads like a virus.
This link may explain some of the ideas behind how HN works:
http://www.paulgraham.com/hackernews.html
I hope that helps! Stick around; it's just a different culture with a different agenda.
Humor is allowed of course, and sometimes it's highly upvoted, but it tends to be humor that is on topic (and so usually about tech or the tech industry) and also as a part of personal stories. People especially have their guard up here because this thread is tangentially related to politics. And like anywhere else, you have to make the right joke for the room, as in your joke needs to be somewhat harmonious with the mindset of the majority (especially if it's off topic, not related to tech, or inflammatory).
Your original problem was that glib comments aren't substantive either, so they're deprecated here, especially when they have an uncivil tinge.