I think there is groupthink in HN even on non-technical topics, but it's much more subtle. It's about that every problem should be resolved using a rational argument. I think arguments appealing to intuition, emotion or authority are likely to get down voted. I am not saying it is a bad thing, that bias is part of why I read HN and not some tabloid. However, I don't think rational thought is perse the best answer to every question, because it's inviting to make incorrect assumptions.