If the nutritional density of the food you are eating is the limiting factor, then prioritizing meat makes sense. But in the USA it's a lot more common to have

If the nutritional density of the food you are eating is the limiting factor, then prioritizing meat makes sense. But in the USA it's a lot more common to have the opposite problem, people are eating too much. In which case focusing on less dense foods can make a lot of sense from a health perspective. Variety also is important to avoid various micronutrient deficiencies. That's one thing that makes Vegan diets more difficult (but if you're overweight it'll probably still help just by reducing your calorie intake, much like most big diet changes).