It is possible to have a moderate debate over strongly-held opinions, so long as everyone is capable of and willing to distinguish between facts and opinions, and agree to differ over the latter. In discussions over which is the 'best' programming language, you can find examples going this way, and examples turning into flame wars. Only the former are worth following.
IRL you can, on the internet the former is much rarer and only works on small groups where the community part is important. And on Twitter or other places where people don't know each other (HN is no exception even if there is a moderation system) it just never happen.
