The first and most obvious answer to me is not all organizations have or use SalesForce or SAP. And the second is that those platforms have specifics focuses Sales and ERP. As a person without either SAP or SaleForce, I’m not clear how well setup SAP is setup to do advanced analytics or modeling on Sales information or SalesForce is setup to do the same on ERP data. I see real value in bringing both types of data together for analysis and modeling.
Others may want to jump in here. But that is a quick $0.02 from my point of view.