The idea of SAP Build Apps is that business users (Citizen Developers) can and should work more closely with IT (Professional Developers) in order to implement current requirements quickly. Depending on what you want to implement, you may want to have access to the complete code that is generated with SAP Build Apps.
An example could be that the business department wants to use an application and designs the frontend with SAP Build Apps and adds some logic. The professional developers, however, do not want to implement the backend and the final steps in a no-code solution, but in a pro-code solution. In such a case it is important to get access to the code generated in SAP Build Apps.
If you would like to try out SAP Build Apps, here is a guide on how to get Free Tier access.