Can I enable an SFTP server password-less login like an FTP server?

It is possible to do this but not straight out-of-the-box.

You will need to use the 'none' authentication mechanism which by default always fails. I have created a version of this that succeeds which you can download from the link below.

You will also need to add the following code in your Daemon.configure to add the mechanism to the supported list.

sshContext.supportedAuthenticationMechanisms().add("none", NoneAuthentication.class);