There's a huge difference between an informational email "somebody just logged into your account, was it you?" and 2FA workflow which does not let you log in without entering proper code. The latter is a security feature, the former is at most auxiliary informational feature.

> I'd definitely call this 2-factor authentication -

You'd be misunderstanding what "authentication" means then. Notification and authentication are different things. Email is notification, not authentication. Confusing it means either not knowing what authentication is, or purposely confusing matters to present issue as something it isn't.