It’s hard to be surprised that “eugenics, but the good kind, just hear me out!” and “state’s rights, but not the disingenuous lost cause kind, just hear me out!” are a tough sell with complete strangers who have no prior reason to trust you or be interested in your opinions.

YC News people generally seem to prefer to hear the truth, especially from sources that appear knowledgeable. I've had people here comment in reply to me saying I've "changed their mind". That never happens on Reddit.

Reddit has cliques, quasi-religions, and fads. Anything contrary to the group-think is mercilessly voted down. Intelligent, thought-out counter arguments that aren't entertaining are especially likely to garner lots of downvotes. Not only do the readers feel "personally attacked" by contrary opinions, there is also that ever present undercurrent of anti-intellectualism of typical Americans that makes intelligent discourse distasteful to them.