Exactly what science are you basing this opinion on?
Laying feeds with average 14-16% protein(meant as a MIN for small bodied layers e.g. leghorns etc.) are not optimum for our larger breeds (especially dual purpose heritage birds) where 21% or so meat bird with real animal protein seems to be the best (even some would argue compromise) for a mixed age mixed bird flock.
Modern commercial layers need less protein and more calcium and vitamins than meat birds to replenish their bodies for egg production. Higher protein meat bird feed is meant for faster growing, heavier bodied meat birds, with little to no egg production. Feeding too much protein, especially to growing layer types, can actually harm them. It can cause overgrowth in muscles and tendons creating leg problems. It can also delay egg production and cause laying problems.
I can find science studies in my back archived links, but a simple review of feed labels comparing meat bird feed nutrients to layer feed nutrients to even all flock feed will give you evidence. You will see substantial differences in vitamins, minerals, amino acids and additional elements.The feed companies base their feeds and profits on years of science nutrition experience with extensive research studies to produce the best type of feed for production needs in the shortest amount of time with the best feed to production conversion for the animal type.
Most people on BYC own commercial lines, or commercially influenced birds. Unless you are a breeder who is working from ground one and specifically manipulating birds for specific qualities, the feed companies have done the research for you.
LofMc