I've inherited a farm where previous "admins" decided to make undocumented changes to the file system to protect users under the guise of governance. This meant removing ribbon options like Workflow settings and anything related to Sharepoint Designer.
I was able to acquire a stock CMDUI.xml file from an untouched farm and replace that in our farm where modifications were made. IIS was reset, browser cache was cleared and the buttons do not reappear.
This leads me to believe there might be customizations elsewhere. What other files in the hive have an influence over the ribbon that I can check? Would ONET alterations cause this?
Edit: I've reviewed Andrew's article on MSDN and none of this is being employed in the farm, leading me to believe this is all file system driven.