Interesting. If you're right, the manual leaves out the rather critical "or the default identity file" bit:
> Specifies that ssh(1) should only use the authentication identity and certificate files explicitly configured in the ssh_config files or passed on the ssh(1) command-line, even if ssh-agent(1) or a PKCS11Provider offers more identities.
> Specifies that ssh(1) should only use the authentication identity and certificate files explicitly configured in the ssh_config files or passed on the ssh(1) command-line, even if ssh-agent(1) or a PKCS11Provider offers more identities.