If it works for Wittgenstein and Oliver Sacks, why not?
I have this friend who eats cheerios every morning for breakfast, alternates tuna/pbj for every lunch, and finishes that off with veggie tacos every night for dinner. There's nothing wrong with that, right? Eat some oranges to stave of scurvy, sure, but I can't think of a reason for this guy not to stick with this and use the brain for something better. Like, philosophy or online tetris.
(That online tetris is addicting. I'm hooked on two player battle tetris with the monster map.)