people like that are often times under medical care, and have very little physical activity. Nutrition is an easier thing to balance with the aid of daily blood testing and a low caloric requirement.
As someone who experienced the reality of tube feeding, it's not so easy as a single product. I was given supplemental amino acids, fish oils and vitamin boosters which were powdered and mixed with sterile water before use, alongside whatever the meal supplementation was during that day (things similar to ensure)
Think about people in comas, people who have parts of their jaw removed due to various oral and throat cancers.
If they can get the price down I'd probably try it too. Can't be worse than a protein shake as a post-workout supplement.