Maggots generate a potent brew of tenderizing proteolytic enzymes. Sterilized maggots are seeing increasing use in medicine - basically for the same reason (to destroy dead/devitalized tissue). Sterilized maggots would be added to a fresh cut of tough, lean meat and allowed to work. Before cooking, the meat would be gently heated from below, encouraging all maggots to evacuate. By which I mean get out of the meat. The supremely tender meat would then be prepared and served. The tunnels left by the maggots would also allow better penetration of sauce / marinade. The diner would never know.