The existence of botnets does complicate matters, though, as you note. In general, I don't agree that this is a matter for site designers; the more we try to p

The existence of botnets does complicate matters, though, as you note. In general, I don't agree that this is a matter for site designers; the more we try to protect the users from themselves, the more it will be our liability when we ultimately fail (and we will fail in the end).