[Pitarou]

No. Of course not. Plumpy'nut is just an example. But there are formulations for people with digestive ailments, military rations, and so on.

Alternatively, it's perfectly possible to design your own "Soylent style" diet, optimising for cost and convenience. I knew of someone (friend of a friend -- a rather eccentric math teacher) who did that many years ago. A large part of his diet was spaghetti and vitamin pills ... not so different from Soylent, really.