> banks aggressively lock out accounts being brute forced This is good, because it means people can't brute force the 5 digit password they forced you to use,

> banks aggressively lock out accounts being brute forced This is good, because it means people can't brute force the 5 digit password they forced you to use, but also bad, because if someone doesn't like you, they can easily block access to your bank. If the account numbers are sequential, or otherwise patterned, they may be able to block access to all users without using all that much bandwidth.