The problem with your analogy is that a traditional diet might be missing nutrients we know that we need (most people don't track very closely) and might also c

The problem with your analogy is that a traditional diet might be missing nutrients we know that we need (most people don't track very closely) and might also contain things that are actively harmful which Soylent does not contain. Lots of people eat traditional diets and have lots of nutrition problems. To make the issue with your analogy clearer, note that you could invent any somewhat edible product and make the claim that adding it to your diet makes your diet safer, because of the possibility that it contains nutrients we need but which we don't know we need.