This seems to be a variation of the “secret key”/“keyfile” idea used by other password managers, which has already been requested.
The main difference being that the feature requested here is to use the locally stored secret when logging in to the accounts stored in the vault, whereas the existing feature request uses the locally stored secret when logging in to Bitwarden itself.
@moremoresp — you referenced the Lastpass breach, but your proposed feature is not useful unless you have a weak (crackable) master password. And someone with the resources to crack your master password would probably also be able to brute-force the 2-4 character pepper that must be added to the passwords that they now have access to.