R Sgr,
To give you a simple example -
When we create a new CMR (customer master record) e.g. 1000. This customer is having an Account group ZZZZ.
This number represents a customer with its role (is it an ordering customer, or is it where the goods have to be delivered etc.). Suppose this customer is an ordering customer (SP).
The assignment (configuration) of Partner function to Account group, SP -- ZZZZ, makes the above scenario possible. (customer 1000 is an SP)
If you donot maintain this configuration step, then customer 1000 can not be created as SP (sold to party).
These type of queries make good material for interesting testing. Try it in IDES.