If I were a bank, I would want to send statements containing financial data only to secure places. So that means something like Google, where they have a serious security team protecting accounts and not something like Ed's ISP and Bait Shop.
The threat would be from people cracking Ed's and getting the statements there, possibly without the sysadmins at Ed's ever knowing that it had happened.
What does that have to do with security? Geniune question. I really don't see what attach vector this prevents