Whether the debt "could have been yours" isn't relevant, what's relevant is how it showed up there. If someone fraudulently signed up for a Comcast account using your social, and they obtained your social via the leak, then yes the leak damaged you. You could go after the difference in your refinanced interest rate now v. what it would have been had you gotten it at the first request (are you paying 0.1% more because rates went up a week after your denial?) and possible the additional interest paid between the denial and the successful refinancing.
But if the Comcast account showed up on your report because someone fat fingered a social and there was no fraud, the leak didn't damage you at all and it was just bad luck.