Facebook on the other hand is a network for the exchange of private or personal information, including for example people forming groups about particularly sensitive topics (abuse experiences, disease and so on), in which personal identity is important to not open yourself up to potential intrusion by people who are not trustworthy. (Cynically enough stalkers for example trying to inject themselves into support groups)
Which is also of course why privacy and identity considerations between HN and Facebook differ.
No, it's not for me.
It seems exactly the opposite to me: I would not want to use my real name to publicly discuss sensitive personal topics.
For example, I may not want my friends or employer to find out that I'm a drug addict. In many workplaces, it could cost me my job. What if someone else in my support group happens to be a co-worker of mine?