My guesses: 1) People had terrible teeth 2) Cooking devices were unreliable 3) Houses were cold so it was difficult to keep things warm without them continui

My guesses: 1) People had terrible teeth 2) Cooking devices were unreliable 3) Houses were cold so it was difficult to keep things warm without them continuing to cook & soften 4) People were accustomed to institutionalised cooking (boarding school, army, servants) 5) Bad practice was passed on through "Cultural acquisition"