Step 1 - You enter invoices first.
Step 2- Then you validate invoices that you have entered (you can do that in a batch by running validation program).
Step 3- Then you pay the validated invoices.
Lets say we have a dispute with a supplier and the management decided to hold all those invoices that are still on step 1 (entered but not validated) but not the invoices that are already validated (step 2). This type of functionality comes handy.
Oracle caters to all kind of different requirements. Not all functionality has to be used to every one.