Some percentage of the nasty things people say on web forums are said half-jokingly and offend because half-jokingness is hard to convey in text, but I think the majority are genuinely nasty.
This is often credited for Facebook having more 'real' content than MySpace and Friendster.
As you've touched on, allowing people to find you on hacker news would also be a benefit.
Next I'll see a reply from cyberguppy.