Comment by manquer

It is still the rules for Gmail (https://support.google.com/mail/answer/7436150?hl=en).

It would be feasible to change something like that without breaking security now.

Google can hardly start allowing/routing a new account for first.last@gmail.com when you were getting it for years even though your account is firstlast@gmail.com and sensitive communication like say from your bank would routed there.