'The myth that meat is hard to digest is all it is, a myth.
Grains, seeds and nuts are a lot harder to digest for humans.'
It seems that the above comment, may be a bit of a stretch. Quantity consumed, and methods of preparation is important for meat, grains, seeds, and nuts. The time and energy required to digest meat protein is quite long compared to the other forms of protein, and definitely incomparison to carbohydrates. When meat is consumed, it is more nutrient dense than other forms of food, and a person gets more nutrients from less amount. If a person eats meat in quantities compatible with acid and enzyme production then digestion isn't difficult, though time of breakdown is still longer than other forms of nutrients.
And with grains, seeds, and nuts, these can be eaten and digested faster and more efficiently. Enzymes are in place to help with the breakdown starting in the mouth. However, natural components of these foods can affect mineral absorption, which is why ancestral peoples developed ways to prepare these foods for consumption. Soaking and fermenting are vital to properly preparing these foods for consumption which will eliminate the health depleting aspects of these foods. Likewise, raw meat requires fermentation in order to be eaten safely, otherwise it must be cooked which also affects its digestibility.
I'm not arguing meat vs. veggie, just noting that the above statement is a generality not based entirely on facts.