Imagine the following scenario: A user syncs a SharePoint document library using OneDrive so that he can have a copy of the documents on his machine. When he doesn't need them anymore, he deletes the documents from the machine (which is a sensible approach). OneDrive syncs the changes and deletes the documents in the SharePoint library. User notices that the documents were deleted, opens the recycle bin and restores them. One Drive syncs all the documents back to the SharePoint library and all is good again. NOT!