That's all good....I agree with the OP...Just then don't step on toes that offer other ways of feeding...Yes, I absolutely understand people who can't afford proper feed, housing etc...Why I rescue Animals in the first place...I raise Muscovies, *many* of them, and I have brooder and broody raised them. Brooder raised ones fed medicated only feed actually gain weight and grow *much* faster (~2 times as fast) than broody raised. Muscovies are quite hardy compared to what I call "quackers" (Mallard derived breeds). Broody raised Muscovies can thrive with very little "duck/chick feed".
The OP has a limited budget, and I respect that. Ideally the OP would go to a feed store and buy a bag of food for duckling or chicks, and a niacin supplement, but that's not an option for many people. The duckling seems to be doing quite well eating the home brew, and it might benefit from having some dry cat food added, which will bump up the protein a little.
You asked "what gives?" Well that's my answer.