LinkedIn is written almost entirely in Java, so Devise would not have worked out that well. Using something like jBCrypt would have been almost as easy, though

LinkedIn is written almost entirely in Java, so Devise would not have worked out that well. Using something like jBCrypt would have been almost as easy, though -- if they'd thought of it from the beginning. The failure here is just that whoever wrote the auth code didn't know that it was a problem, or thought (incorrectly) that using something like bcrypt would be significantly more effort.