It's "Two Factor Authentication", not "Second Factor On A Single Device You Always Have On Your Person Authentication".
That second factor needs to be separate from the originating authenticating service, not that it has to be on a single device hidden away kept in a safe, or on your wrist, or in your pocket. It could be a single device [a server] running bitwarden and you're viewing it through a browser on your <whatever>.
Not everyone wants to follow every single recommendation from a data security perspective, and it becomes an anti-pattern when laymen start using workarounds to not have to comply with the safety recommendation of the week.
That second factor needs to be separate from the originating authenticating service, not that it has to be on a single device hidden away kept in a safe, or on your wrist, or in your pocket. It could be a single device [a server] running bitwarden and you're viewing it through a browser on your <whatever>.
Not everyone wants to follow every single recommendation from a data security perspective, and it becomes an anti-pattern when laymen start using workarounds to not have to comply with the safety recommendation of the week.