tml_allow_user_passwords()

function tml_allow_user_passwords() {
    $user_passwords = (bool) get_site_option( 'tml_user_passwords' );

    /**
     * Filter whether users can set their own password upon registration or not.
     *
     * @since 7.0
     *
     * @param bool $user_passwords Whether users can set their own password upon registration or not.
     */
    return (bool) apply_filters( 'tml_allow_user_passwords', $user_passwords );
}

View src/includes/options.php, line 186 on GitHub