i don’t see how that affects the nutrition of the beef. You can only mix so much fat in because it melts away when you fry the burger up. They aren’t using lymph nodes and such the FDA requires them to call out non meat ingredients. The beef doesn’t lose nutrients as the pieces get smaller. They weren’t using prime cuts in the 80’s, either.
what’s available on google is not really agreeing with your proposition here outside of grain fed/grass fed, and even there the difference is slight and mcdonald’s was definitely never serving grass finished beef. Your guarantee is worthless, you’re just spreading baseless FUD. There’s plenty of real reasons Mcdonald’s sucks you don’t have to invent spurious claims about the meat.