I think it's likely humans are evolved to eat cooked food. The guideline don't eat anything you wouldn't eat raw isn't intended to dissuade people to not eat cooked food, but rather to serve as a heuristic for foods that were probably less commonly eaten by our ancestors. It's unclear to me how accurate the heuristic is. A big counterexample is tubers. Tubers are widely eaten by modern hunter-gatherers and are toxic when uncooked.