First off what are the obvious reasons you are talking about  And what linguistic standards scholars and consensus are you referring to There is no such thing   The Dravidian theory is just that a false theory that was suggested but not proved by Colonial rulers some  years ago  It has largely been debunked and rejected by most modern historians including the famous Dr Dani a pioneer and the foremost expert in Indus Valley Civilization  Get your facts straight and please only post veriable and accurate data in this article  Cheers