I think she means something like this:
Someone has two accounts.
However, they forget the password to one of them, and is entirely unable to retrieve it, since there's no "password remembering" thing. (Some sites have that, as far as I know.)
The account with the forgotten password could be hacked, since the original owner can't change it (since often changing one's password also helps protection, in most cases, I think).
Like what happened to me in a way.
After 2 September, I somehow forgot the new password for my first TV Tropes account, and had to make a new one ("Shane Bane Neumann").
Apparently, though, because the "SBaneN" troper account didn't have an e-mail associated with it, it's impossible to get a password reset for it.
But that's unrelated, though, right?