The thing with email is that it's very easy to create instantly thousands of new accounts. Fake FB accounts are much harder to make, although still possible.
By the way, it's also possible to buy a new account with BTC or LTC: https://steemit.com/steemit/@anonsteem/bypass-steemit-email-phone-verification-with-anonsteem-over-200-users
I've recommended AnonSteem for potential users who can't or don't want to use phone for making a new account.
Very good to know. I will bookmark it. Thank you very much.