If your master password leaks you are exposed on every website where you used this scheme (and you should then change every password), so on the security side this is inferior to a master password granting access to uncorrelated passwords.
I know, it's not perfect, but it beats carrying around password files between devices.
By the way, I'd prefer to have a password manager on my phone (or smartwatch), and have it beam my password to my keyboard by NFC. But this solution does not exist yet.