If I play chess, and someone changes the rules so pawns can now move in any direction, and rooks can now move diagonally, and kings can now move any number of squares, am I still playing chess?
That said, if you say to the person you are playing against, "But those are just optional rules. You don't HAVE to play it that way. I am, but you don't have to. It's up to you if you want to challenge yourself that way or not."
Do you think the other player is going to not use the new rules when the entire game is now designed around the new rules?
Comparing chess to dnd is apples and oranges. Chess has a set of rules where you HAVE to play that way or else you can't play the game. In DnD the rules are there as a guide. If not a guide and you HAVE to play 5e the way it is, then homebrew rules would not exist.
It is not that far-fetched. There are flavours that you can change freely - chess should not be black/white, you can use other colours (this is what Dms change in DnD). It will not change the game. But if you are changing the fundamental rules, you have another game.
There are core mechanics in DnD that no DM will ever change. Rest system and action economy are at the very heart of the system. You change one thing - the whole system falls apart. Food eliminates healing and rest, breaks the rule of Bonus Action, makes some spells useless, changes encounter levels.
With that addition, you literally bring checker's rules into the chess game. Systems are incompatible - it's either DOS or DnD, together they do not work. Once again, Larian did not say "we are using our homebrew variation of DnD", no. What was promised is 5e, and 5e people expect.
Since I am seeing some people wanting strict 5e rules and ONLY 5e rules. Let's take a look at the D&D Player Handbook, on page 185 section FOOD AND WATER. It states:
"Characters who don't eat or drink suffer effects of exhaustion. Exhaustion caused by lack of food and water can't be removed until the character eats and drinks the full required amount."
I know I mentioned eating food to replenish health either during or after combat, to which some are like "NOOOOO" but according to D&D we need to consume food and water or our character get's exhausted. Thereby, technically what I said isn't entirely wrong or dumb. It may not be for combat but you still need to consume food and water.
I'm glad you brought up this excerpt. "Characters who don't eat or drink suffer effects of exhaustion. Yes! Absolutely. This is why I think that food COULD be used and SHOULD be used as a homebrew method to heal up during short and long rests both. Absolutely 100% they should come into play more. We get SO much food in the game that Larian could easily use this as a method for healing in the context of short/long rests both and that would make total sense.
I've proposed before, and I'll do it again because I really think it's a great idea:
Make Short Rests unlimited like they actually are in D&D 5e rules. If you don't want to use the Hit Dice rules because you think they're too confusing for people, or you just don't like them, then fine. Short Rests have a lot of limits already. Spell Slots aren't restored for clerics and mages unless the mage uses their Arcane Recovery, which they only get like a certain spell slot allotment for that anyway. So the biggest unlimited class is Fighter who can reset all their special abilities every Short Rest. This makes them far more valuable for characters to push their party longer. Have a fighter in the party who gets to reset all their abilities every Short Rest and even if your mage and cleric run out of spells, the Fighter and Rogue can still carry the team pretty well. Even IF your mage and cleric run out of spells, they still have Cantrips that they can do. Not as tough, but that's the point. Mage and Cleric spells are tough. They do a lot of damage, especially at higher levels. So that is why they have to be limited to long rests for their spells to be recovered.
So, unlimited short rests, BUT they require food. That way, food becomes SO much more important. In the rules you quoted, food and water are essential or you become exhausted, but time is only progressed in BG3 by Short and Long Rests. A Short Rest is 1 hour-ish of time. A Long Rest is sleeping for 8-ish hours at the end of a day. So when would your characters naturally eat? During Short and Long Rests.
So how do you limit Short and Long Rests? Food cost. Camping Supplies. Suddenly, ALL those camping supplies become SO much more valuable, and NOW you'd have a reason to keep them on your party, at least some of them. Send most to camp for Long Rests, but you still have to keep some on you for Short Rests.
What would the cost be?
I proposed a Cost Per Character Level Per Party Member for Short Rests and a Cost Per Character Level Per Character At Camp for Long Rests.
So you take 4 party members with you who are Level 2. Short Rest Cost would be 8 Camping Supplies for a single short rest. You start out with 40 Camping supplies in packs per character, so 8 Camping Supplies for a Short Rest is hardly limiting.
However, as you begin to spend them more frequently, your Camping Supplies will start to dwindle pretty quickly. Suddenly, those fish and apples and cheese wheels and ribs and wine and so forth become so much more valuable ESPECIALLY if Camping Supply Packs can't be broken down and can only be used for Long Rests (which I don't think they should be. I think, as many have suggested, that Camping Supplies should be able to be broken down or created by combining a bunch of food items into 1 40 Camping Supply pack. Requirements for Crafting a Camping Supply Pack = 1 backback + 40 camping supplies worth of food/water, etc.
You level up to level 3. Suddenly, Short Rests are now 12 Camping Supplies per Short Rest because you're now at Level 3 and you have 4 party members. Want to spend less Camping Supplies per Short Rest? Take only 1 or 2 party members with you on a quest. Don't Short Rest with all of them. Now, suddenly, it's much more important to manage you party and determine how many you truly need on your missions. Or maybe Gale doesn't need to rest because he hardly did anything. Unchain him from the party and Short Rest. Only those chained together gain the benefits of the Short Rest. So, you only have 2 who need a short rest, and they're both at level 3. That would only require 6 Camping Supplies.
Long Rests would be 2 Camping Supplies Per Character Level at the Camp. So if you have all the origin characters at your camp, even if they aren't in your party, you have to spend the cost for ALL of them because you are feeding ALL of them and supporting ALL of them. Have 6 Level 4 characters at your party? That's 48 Camping Supplies. That's still not a ton because you get so much food, but it certainly would start adding up a ton if you started to long rest a ton. Have Volo at your camp? Add another couple of Camping Supplies to your Long Rest OR kick Volo out of your camp. Have Scratch and the Owlbear Cub? Add another couple of Camping Supplies to the Long Rest. Dogs eat. Owlbears eat more.
But again, you can pick up tons and tons and tons of food in the game, so this still wouldn't be limiting players that much. However, it does limit them to a certain degree, and it certainly encourages them to NOT rest endlessly.
At one point, I had over 600 Camping Supplies in my chest at camp. 600!!!! So, at level 4 with my 6 characters plus Volo and plus Halsin plus Scratch and the owlbear cub (minus Withers the Talkative Skeleton because he doesn't eat), at the most that would be like maybe 60-80 Camping Supplies or so per Long Rest. Short Rests would only be 16 Camping Supplies.
Ah! Now Short Rests become SO much more important because now people are going to want to Short Rest more frequently since it's much less food resources. Now they won't spam the Long Rest system so much, and when you hit Level 5 and Wizards can start casting Fireballs and Lightning Bolts, the game balance won't be totally obliterated by players Long Resting after or before every fight.
And so, food CAN be used to limit resting the way they are currently trying to design it, and it makes sense because people are using the food to renew their strength during resting. Short and Long Rests are supposed to heal HP because characters are eating, drinking and bandaging themselves and repairing their armor and equipment. That's the entire point of them. So it makes sense that food and water items should be used as a homebrew method of restricting abuse of the rest systems.
AND this puts more of the strategy into the hands of the players. Instead of limiting Short Rests to 2, players get to decide how many short rests they want to use knowing that they slowly dwindle their food resources every time they use them. Knowing you have someone like Halsin sucking your food resources in your camp, you have to decide if keeping him around is worth it. Same with Volo. (Scratch and owlbear shouldn't cost too much. They're not high level.) Suddenly, you might decide you don't want Astarion around because he annoys you anyway and he's just a bum draining your food stores... or maybe Gale is someone you don't like, so you boot him because he's eating your food at camp.
This makes it a game. This makes food important and realistic and immersive.