It's not like balance was really important in a game like DF where you have so much freedom; Efficient or not, if I want my fort's economy to run entirely on buckets of cow milk, I can do it...
The thing is, that's really only true so far as gameplay choices don't have objectively measurable consequences... and they do. But even then, that's not really the whole point I'm getting at.
Running a fortress entirely on cow milk is a massively sub-obtimal choice. Whereas a single grower, cook, and having the haulers swing by to pick up eggs can cover basically all food needs with surplus food to trade away for profit, cows produce enough milk to only barely cover two dwarves' hunger per cow.
If we assume that you can have a max of 50 cows, then because cows have an average max age of 15, you can assume you'll need 2-3 bulls, plus have about 8% of the population being calves, so you're talking about a maximum milk-producing herd of 43 cows, so you've got a fortress population cap of 86 dwarves IF you are absolutely efficient in running them.
That's before we even consider pasturing, the micromanagement that comes with having to watch to ensure you don't overgraze (even if given large enough pastures, animals in DF tend to get "stuck" in corners of the pasture and starve themselves to death), the amount of dwarf labor that will have to be spent milking and re-pasturing the cows, plus the micromanagement because
of course the jobs will be canceled off of repeat when all the cows are inevitably milked at some point, but where there is no indication when the next milking is potentially available, meaning the only interface solution the game gives you is to keep spamming the order until it doesn't give you an error message. Oh, and if you do have 86 dwarves, then you can't afford to have even the slightest gap in milking and cheesemaking, or you start sliding inevitably towards starvation...
The bottom line is that cow's milk just doesn't make sense from any rational standpoint. It's like saying you have the choice to complete a marathon by crawling on hands and knees the whole way. Yes, hypothetically, nobody's stopping you from doing it, but you're going to either quit early, get really hungry by about the third day of crawling, or just plain ruin your knees... and it's not like there's any advantage to crawling over jogging like you're supposed to.
Yes, sure, you can do anything you want in a sandbox, but that doesn't mean that game mechanics don't inherently have feedback upon the consequences of your choices, and implicitly, if not explicitly, make some strategies more effective than others.
Or in simpler terms, no, not everyone is a special little snowflake. Some playstyles are just plain wrong. I can have my fresh embark full of naked dwarves with no training or preparation dig straight for the HFS, but all that does is lead to repeated crumblings. Any playstyle that doesn't ensure dwarves have access to adequate food and shelter is not experiencing the game in your own special little way, it's simply failing pretentiously.
Games are, fundamentally, sets of rules that provide feedback upon the decisions we are making, and the rules chosen inherently enforce certain types of choices to accomplish particular goals the game sets out for its players. For as far as there are goals set forth by the game, explicit or implicit, games not only judge whether a player is making an optimal or sub-optimal choice, but it is the very rudimentary purpose of games to
teach players to act in the manner that optimally accomplishes the goals the game sets out for them.
The only reason DF is even capable of allowing so many types of sub-optimal choices in the first place lies solely in the fact that DF is such an easy game that as long as you accomplish a couple extremely rudimentary tasks, you can spend the whole rest of the game dicking around however much you want.
But even that isn't the point I was making, even that's when the game is working more-or-less according to plan.
Game balance between food types is efficient or inefficient, but much of DF's game balance is straight up game-breaking bugs, and destroys all choice in the matter. The new needs system has several forms of needs that are outright impossible to fulfill. From dwarves declaring they will not be happy unless they eat a non-existant animal to asexual dwarves uninterested in marriage complaining that their needs for marriage are not being met, the game's balance tips into simply needing to find exploits and workarounds to simply get past the broken parts of the game.