You can get large amounts of food for the long playthrough, by defeating Demon King many times and each time getting 200 of food. There also are a few ways to farm food that will destroy your Purity, but aren't really the cheats, glitches, etc. So, there's really no excuse to cheat except being lazy.
Farming money and food would destroy balance. Yes, the game is designed for multiple walkthroughs — as any visual novel style game, in fact. Some choices are only available once, some outcomes are the Game Overs (plenty). It's working this way pretty okay. I play the Orcblood Thief with all the companions gathered eventually (as soon as my Charisma is enough), and even without bonus points I manage to get to Demon King 100% of time. And I always was a casual player to be fair, so... You only need to get hooked.