The problem with that practice is that even though you know where the ingredients come from, you can’t assume the recipe adheres to pet food nutritional quality standards. Pet food companies must test their foods for nutritional adequacy; there is no comparable assurance regarding home-made foods.
<><><><
In my experience, folks who go to this trouble have done their research and know a thing or two about nutrition for canines. I don’t think we’re talking about feeding the dog table scraps exclusively.
Do you have the same concern with people who make their own baby food?
With some people, yes. Some of the ways people feed their kids are horribly unhealthy. Some of the worst are those who want to give their kids "healthy" vegetarian or vegan diets, which can permanently impair brain development.