Our customers may requires to control Workflows to avoid creator approval on documents submitted to workflow. This could be controlled by the system where set Disallow approval by submitter control as Yes.
You can find this control under System administration| Workflow| Workflow parameters (see screen below)
Assume that the same user creates an invoice and normally he is the one approves the invoices, but in this case the workflow engine will prevent the same user to create and approve document and throw the exception shown in the following screenshot:
AX / Dynamics 365 For Finance and Operations blog 