I highly recommend you read (or listen, the audiobook was great) to Conquistador by Buddy Levy. It might change your mind on this point. It tells the story of

I highly recommend you read (or listen, the audiobook was great) to Conquistador by Buddy Levy. It might change your mind on this point. It tells the story of Cortez from the day they arrive on the shores of Mexico to when they take over the Aztec empire, where there were still many, many native peoples. The European advantages were many more than just disease... for better and worse.