I actually think there's a clear explanation for this: HN is much larger than it seems. There are millions of users. Every subgroup/tendency is going to be represented in a population sample that big, except for utterly obscure ones.

Which subgroups/tendencies show up in the comments is therefore more a question of the particular thread: the title, the topic, and the early comments. If it seems like "HN would be better than $X", that's only because we mostly manage to avoid the stimuli that produce $X responses.

Thinking that HN would be better than <insert any bad behavior here> is a bit too hopeful of an assumption. Everyone is prone to bad / ignorant behavior. HN users being no exception.