What's the problem with protein/fat bars? Rancidity? There are fats (possibly not those found next to meat) which can be more shelf-stable; I wonder if you co

What's the problem with protein/fat bars? Rancidity? There are fats (possibly not those found next to meat) which can be more shelf-stable; I wonder if you could use those fats, protein, and chemicals extracted from the tasty fat to have the right stability, taste, and nutrition profile. But that would be "evil food science" so people wouldn't think it was "healthy" I guess.