And China also, the Weechat app uses them for so much: paying at restaurants, adding contacts, etc.
For marketing they're stupid.
For other applications where the QR code itself is grandstanding as being somehow important or novel it's ridiculous. In other words, anything that says "Scan our QR code" is an automatic fail because you'll have to open a special app to read it, not the payment app that just happens to use them as a method of data exchange.