It doesn't have to be, true, but it is heck of a lot healthier and easier if it is meat.

I have nothing against veganism and vegetarianism. It is a lofty goal.

But strictly on health standpoint, no amount or kind of plant food can (currently) beat healthy whole animal tissue (you should really eat more than just meat and also not all animals are same way healthy to eat).

Now, this doesn't mean there can't be better plant-derived foods in the future. A protein is a protein is a protein.

The problem with plant based protein is they come in wrong concentrations, wrong combinations, they are missing some stuff or they have extra things that make protein more difficult to absorb. If we can fix these points, we can have healthy plant based diets.

But really the main benefit of meat is that you get close to the right concentrations of everything by very definition. If you eat whole animal, that is. We have evolved to eat meat and only evolved to eat plants to supplement some small things (mainly vitamin C and to eat fructose and alcohol to get fat for the winter).

With this, any stupid person can eat relatively healthy diet. You just put a steak in your mouth and you are 80% of the way there.

On the other hand eating healthy diet on plants is a difficult task requiring planning and diligence that I think half of the population is simply not equipped with brain power to execute correctly.