Please don't invent motivations for the statements people make when you don't like what they've stated so far.
If you don't want people browsing your passwords, you can't ever give them access to your user account or your unlocked desktop. That's it, that is the entire solution. Any other method of protecting the passwords is vulnerable as long as the potential attacker has physical access to the unlocked desktop.
Now, perhaps some of this is mitigated by the fact that most of those friends, coworkers, significant others won't know how to install a keylogger or install extensions - but some small percentage will anyway, and those users who were lulled into a false sense of security will have been just as exploited anyway.
If you don't want people browsing your passwords, you can't ever give them access to your user account or your unlocked desktop. That's it, that is the entire solution. Any other method of protecting the passwords is vulnerable as long as the potential attacker has physical access to the unlocked desktop.
Now, perhaps some of this is mitigated by the fact that most of those friends, coworkers, significant others won't know how to install a keylogger or install extensions - but some small percentage will anyway, and those users who were lulled into a false sense of security will have been just as exploited anyway.