> … legally they can't give them any more specifics.
Could you please provide a source for that? That can be an important distinction for an employee. For example, when answering the question "Why did you leave your previous job?" It's important for the now ex-employee to have accurat information.
I elaborated on that - mainly just that anything HR says can be used as evidence in wrongful termination lawsuits; even if nothing happened, it could be enough to trigger further discovery, which ultimately means spending tons of money for the company in legal fees. Being a top performer then getting fired for poor performance is suspicious in any case.