Ask HN: Why haven't signup confirmation emails died yet?

I have been thinking about confirmation emails today and cant think of a single reason to actually send them. They are annoying and must have a user drop off rate. I know I personally don't return to some low priority sites if I'm to lazy to load my email or it takes more then 20 seconds to get the email.

What is the point and why hasn't this practice died yet? Are there any benefits I'm overlooking here?