[drbawb]

>Pretty much every single company I've worked for with AD has broken this rule.

It's a lot better now. Ever since companies started moving from on-prem Exchange to O365 in droves I've noticed that most orgs I work with (painfully) updated their domain so their user principals align w/ their O365 mailbox.

There's only one customer I have that still uses a ".local" domain for AD, and they got bought out last year. (By an org that uses a real FQDN.)