RAP Business Service with AND without draft

[pmcfarling]

I was reading through the RAP book, trying to figure out the naming conventions. i.e. C_*_A_D vs C_*_D_D.

I understand the naming convention but the given example has this architecture (See pic below) . I'm struggling to understand why unless it's just for an example purpose. I understand they wanted to show how to take a non-draft BO and draft enable it. But, is there any reason outside of a textbook example to have this architecture? I'm thinking perhaps without draft for a Web API and with draft for a FIORI Elements app? Should make it a habit to expose a service without draft in addition to one with draft and maintain the naming convention mentioned in the book.