It's a fallacious argument in my book. Like comparing apples and oranges.
Say I run a bakery. What I care the most about is the quality of my bread. So much, I spend all my time working on that and only that. So much, I didn't ever bother to have a lock at the door. But it's not even a big deal if someone comes in and poisons one of the bread, as long as the overall quality is increasing!
> SSL is a giant waste of time for Hacker News
Yes, if by "giant" you mean that it takes like 2 hours to set-up, and a small payload for each negociation. But concerning the payload, Arc is not especially fast, so there is room for improvements there to compensate, if needed.
> modulo the fact that people might be crazy enough to use a shared password here.
Not the point, the point is HTTP sniffing.
And anyway, people could use a shared password, making it easier for them (don't overestimate human memory), if HN used (HTTPS and) a "real" password encryption scheme (bcrypt or the like). Why put the burden on the user when you can put it on the computer?