There are entire classes of attack that 2FA protects against that you are completely screwed without.  Some examples: You use a computer that has a key logger, or you get infected with a key logger, or a hardware key logger is installed inline with your keyboard cable.  Someone shoulder surfs you while you log in.  Someone points a video camera at your keyboard while you log in.  Someone uses an RF vulnerability to wirelessly snoop the RF signals as you log in on a keyboard.  You get phished (a good phishing page, not a pathetic one).  You get tricked into entering your password into a popup dialog box that appears to be a &quot;Log in with your Google account&quot; dialog, but isn&#x27;t.