At this point, because there are "dueling document experts" (which I believe is an untrue statement, the overwhelming majority, if not all, say the documents are fakes) and CBS acknowledges that their main "witness" is a DNC operative, it is VITAL that the American public know who the source of the documents is.
If CBS is unwilling to identify who gave them the documents, they are currently perpetuating a smear by not letting the whole story (the TRUTH) out.