Yes I do agree with the article.
As I mentioned in a previous post, it is amino acids that make up the protein of which we are made, so chicken protein is chicken protein and NOT human protein.
Some nutritionists believe that plant-sourced protein or amino acids, are not what they refer to as "complete proteins" as found in meat, and therefore inferior, but as long as the plant-based diet is a varied one, then this is not a problem, as a diverse source of plants will provide all of the amino acids to form complete proteins within the body.
The body will manufacture 15 of these from the diet, but the other "essential 8" not manufactured by the body (and therefore referred to as essential) are found together in quite a number of vegetables and fruits.
The problem with meat, is that this complete-protein has to be broken down by the body into its constituent amino acids to be bioavailable and utilized by the body to form human protein: this takes much digestive energy.
I also subscribe to the "Amino-acid-pool theory" as well and have done so for many years.