It's always easier to assume that your argument is being dismissed because the other side is ignorant or intolerant. As dang points out in a sibling comment to yours, it seems to be universal.

I've found most of HN willing to dive fairly deep on any topic as long as you remain respectful and don't present your self unwilling to actually reconsider your opinion. The problem is that all too often, assholes don't realize that how much an asshole they are comes across very clearly in how they present themselves or their ideas, and many people don't like interacting with assholes. The other problem is that we're all assholes sometimes.