Why is it that some application will define their own users ( maintaining
username and password, defining roles, etc ) instead of using Oracle users,
roles and password management with Oracle Users.

I support a few application running on Oracle and they almost all use users
define in this app. ( They litteraly design a table for users / password and
roles )

My boss ask my to design an application to track some metrics and I'm
wondering what type of user management to implement.

Thanks for your thought

Sylvain