You will have to do that for each site you want passwords for, after they have been autofilled (whereas Chrome gives you a convenient list of all saved passwords). It is also a far more technical method than most people are comfortable with. Slower and more difficult, thus less likely to happen casually.

There is also a significant difference in feeling between the two methods. Your suggestion requires far more intent than visiting the settings page. This is important.

We are not talking about defending yourself from a malicious attacker, we are talking about the moments when you pass your computer to a friend so they can look something up. They can now look up your passwords conveniently and without feeling too bad about it.