I regularly see "posts from dissidents" here on HN, but I do notice that they are all strongly written, well-argued and often contain citations to support their position. Is there an asymmetry in the way karma is awarded to "bubble" and "non-bubble" positions? Probably, but that doesn't mean non-bubble never makes it.
Could it be that karma rewards different things than you believe?
Having said that, people here do downvote based on opinion allignment, which is very hurtful. I've seen perfectly legit comments (with sources) that are out of the norm being downvoted because people just don"t agree with them
that expecting to see the full range of human opinion on any even vaguely controversial topic in a single context is foolish, and that i'm tired of people complaining about "dissidents" not showing up on HN when they clearly do (even if they are (surprise!) in a minority of top-ranked comments.
ps. I never downvote on HN unless someone has actually made a grievous factual error or is being personally abusive.
You'll just get banned.