Ask HN: Why is company letterhead a valid form of auth in 2022?

After filing a violation with twitter support for an account impersonating an opensource project I work on (posting fake news, etc) Twitter has asked that I verify myself as being part of the organisation being impersonated by providing a copy of my business card or a signed company letterhead.

This is not the first time I've been challenged to provide a company letterhead as a form of authentication by a large, reasonably sophisticated company. How is this still considered quality best practice?