This is a very one sided view of SSO. It is vastly easier to manage and strongly secure that single point, for administrators, security professionals and users

This is a very one sided view of SSO. It is vastly easier to manage and strongly secure that single point, for administrators, security professionals and users. You can enforce a much higher security credential, as it only has to be used once. You don't have to worry that your users are re-using the same weaker credential across multiple independent services (hint: they will). Using SSO does not mean you have no defence in depth. You should always consider defence in depth in the context of the overall system. It's not a strong reason IMHO against centralising or simplifying one type of control.