I can definitely understand why it makes sense on paper but what makes me skeptical about it is the places that are relatively isolated from the rest of the world. Places like North Korea make me skeptical, where millions of people live but only a handful of people have had contact with the outside world. Plus if you factor in the North Sentinelese, who still haven't had contact with civilization, the theory completely falls apart. But it's still interesting to think about and definitely fun to map out your connections.