It's done because sometimes 'the obvious' isn't so obvious to everyone else. The intentional uncertaintly and confusion around an already confused event may very well save lives and/or time. Certainly the alternative, running to a soapbox and announcing to your enemies that your personnel are spies and have 'obviously' crashed in enemy territory, is not a good idea.
Oh for goodness sakes. My quipt was meant as humor. If you are going to argue debate and lecture me on a subject that really I don't need any lectures on then I withdraw the quip. I apologize for offending your sensibilties.