The customer can use the CRUD call, but they are trying to reduce the number of round trips and complexity of getting all the subscription information. Right now if a user has several subscriptions they need to loop through and get the two additional fields of data for each subscription, if this information could just be returned with "https://rest.zuora.com/v1/subscriptions/accounts/{account-key}" it would reduce complexity.
Z-Support SME
gelaimr