There's a reason mammals feed their infants milk, not oats. Milk is strictly more nutritious.
Inefficient to produce, sure. Destroying the environment, yeah. Cruel to animals, definitely. Unnecessary, yes. These should be reflected in the price, not nutritional labels.
The idea is good, it just got water down too much. On top of that, there are German laws dictating a certain minimum sugar content for certain products to be called mustard or marmalade for example, or lemonade. Which kind of screwed up if you ask me. But that is more of a national thing.
I looked at the rules and it seemed like a really good idea.
I even got the impression, products got changed for the better in the last year to get a higher nutri-score.