But it also gives you a sense of optional anonymity as your HN account doesn't have to necessarily link with the rest of your web presence. No one can find you in the real world just from you HN account if you don't want them too. And still, the option to provide further information gives you the OPTION to present your credentials and connect "who you are" with the HN account.
I find it really interesting how sometimes VERY simple features are solving relatively complex problems
People/usernames are brands in online discussion, so the way we generally weigh people's opinion is affected by those brands, which is kind of a function of their comment history and any IRL connections. Say, if the username is 'pg', even if it's a hit-and-run comment with not much thought put into it, you view it differently.
However, with the anonymous feature to ask question, I have seen a rapid degradation of the quality of questions coming on Quora. I am not the only one who has felt this way. We can find a lot of people complaining about the quality of questions of late.
Quora on the other hand, has this feature of being able to ask or answer questions as anonymous, and this has resulted in an avalanche of stupid questions and unrelated answers.
We are somewhere in between, while we like to give a real identity like Quora has, we also believe, anonymity is an important feature to have, for many different reasons.
"A good design is something which takes care of both extreme users, and not just a center large portion."
The user feature of a website should be such that, they should feel to interact either as real identity (gets them social karma) or as an anonymous user (without any concerns)