We don't have a lot of research on "food combining" so I think separating the two is used more on an as-needed basis for those with digestive troubles. Sometimes combining certain foods (in whole form) don't allow for proper digestion in those with inadequate enzymes or are lacking good gut bacteria. When the NutriBullet pulverizes foods, it’s reverting food to it’s pre-digested state, reducing the load on the GI system and making them more easily digestible and absorbable. By consuming fruits, veggies and boosts in this manner, many find it less taxing on their digestion as compared to ingesting food in its whole food.
For more, check out this article: Busting the myth on food combining: http://health.usnews.com/health-news/blogs/eat-run/2015/05/12/debunking-the-myth-of-food-combining