I found that very weird too. I've used Dropbox referral links a couple of times in blog posts. When somebody clicks them and proceeds to sign up, Dropbox tells

I found that very weird too. I've used Dropbox referral links a couple of times in blog posts. When somebody clicks them and proceeds to sign up, Dropbox tells me their email address. That's clearly not ok. They shouldn't need to be told this. It should be obvious.