> if someone steals credentials from a subset of users and can use that to gain access to nearly half your customer base If someone gets access to my facebook

> if someone steals credentials from a subset of users and can use that to gain access to nearly half your customer base If someone gets access to my facebook account they can read anything my "friends" have marked as "friends-only". Lots of users want that kind of restricted sharing (both with Facebook and with 23andMe).