well but when being able to regaining access to the account-id that was used you might be able to revoke the certs or whatever.
that LE doesnt have the keys is obvious, I have no idea how to call it in English but I have a finished apprenticeship as a “Fachinformatiker” (at least that’s what we cann it in Germany here)
regaining your account doesnt give you the keys back, but the pki data associated with it, which may be even more important, depending on the situation.
imagine this. an internal person with ill thoughts takes away the cert key, removes the private keys from the original server, and now he has the priv keys to a valid cert he shouldnt have very soon, problem, the company cannot revoke the certs because there is no way to get the account back via email or whatever and that hurts.
sounds far fetched but mis issuances also happen with big CAs which also shouldnt occur