Good point, by logging in you are consenting to their tracking. I must be honest though, I still think it's a fair trade off. I also suspect that making content public might make it worse - people know on HN and Reddit their comments are visible to a huge anonymous constituency and it biases the nature of responses.
Can you elaborate on that? I mean, how exactly does it bias people's response?
The "privacy" of a service can affect people's answer if it is that, private. But Quora is not a super exclusive club: anyone who's willing to spend some time signing up, and who's willing to risk having his posts revealed to his facebook friends because of a new "feature" can get into this club...
So I ask again, what peace of mind does it bring you to know that your answers are behind Quora's walls?
My general feeling is that a lot of content on HN, Reddit, etc. is superfluous and non-value adding. Things like buzzy blog posts, sensational headlines, etc. Believe it or not, lots of PR firms and businesses use HN as a way to promote their features. On a walled garden (as much as my gut reaction is to dislike it) you don't have that issue. There are other scenarios too, I'd imagine you can come up with as well.
