Exit interviews are an opportunity for the formerly employed to air and address their grievances too. I think it precludes a (generally) necessary transfer of information when an email is sent en lieu of a substantive discussion.
As someone who’s been on both sides of the proverbial desk, I’ve come away frustrated but enlightened in some way almost every time.
there's literally zero upside for the employee to say the truth - or anything at all - in an exit interview and basically unlimited downside. maybe you got lucky?