what is benefit of membership provider class if we override all methods?

 Hello,
My question is  what is benefit of membership provider class if we override all methods?
In one of the projects from asp.net site under starter kits. There is a project ADAMMembershipProvider and class( public class ADAMMembershipProvider: MembershipProvider)
In thisclass all the methods ( createuser, ResetPassword ...and others) have been overridden. 
So my question is what is the benefit of using the base membership provider class? what does it do for us?
I really want to know why I should be using the membership provider class? what are the benefits? and how can i implement it in C# asp.net 2.0
 

 

 
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