The advantage of passwordless is that the validation is done directly from the wallet supporting the HAS protocol. Thus, the keys are never communicated, preventing the application used to retrieve them ant to being leaked after that.
Moreover, the initialization is done by scanning a QRcode from the wallet (or in the case of an application on a smartphone a direct communication with the wallet) allowing to create the future encrypted exchange between application and wallet. The system thus prevents any man-in-the-middle attack since only the application and the wallet can encode and decode the messages they send each other.
Amazing very secure I see.... Still research on a personal note