Earlier quoted context omitted.
You know what's also convenient? 1FA. Which, incidentally, when you store you TOTP secrets with your passwords, is what you have.
I mean, if the password manager’s store is compromised, then sure, okay. But if only the application password is compromised then it’s still 2FA since the attacker cannot authenticate with just the password.
The F in 2FA is factor. Satisfying one login request from one factor (password vault) is 1FA. This is why the second factor is normally something that isn't your password vault (historically your head, now a piece of software): a hardware key, a recovery code, etc.
A slightly more generous interpretation is 1.49A (rounds down), because someone with a reused username/password combination. But if you're using a vault with a sophisticated factor, the venn diagram of "people who have your password," and "people who also have your master password," are pretty tight, except for cases where the provide has been breached (all bets are off).
Don't dispose of the second factor for convenience.