The world of Auth has been made miserable with everything having to support OAuth2/LDAP/SSO/SAML etc., plus a million versions of access control, session configs, yadda yadda. Each of these has their own (usually legitimate) purpose, but also each one has to integrate with other providers that each don't follow and/or extend the spec in their own special way. And the pain goes on and on.

Obviously you can make a product that only does really good username/password auth for example, but there's always more pressure to implement more things for another use case.