This isn't about protecting the company. It's about protecting yourself. You're opening yourself to be a witness in a suit (nobody wants that), thrown to the wolves by the company (who will attempt to portray you as a rogue actor) or criminal prosecution.
Now if the company is doing something unethical and it's why you're leaving, then sure write that down as long as you're not admitting personal culpability of any sort.
Likewise, if you feel like you're being set up to take the fall for something, a paper trail can help you.
But otherwise, if you're in an ethical grey area and decide you want to continue to earn an income to, you know, live then there are such things as "inside thoughts".
[1]: https://www.justice.gov/opa/pr/volkswagen-engineer-sentenced...