Well, if you look at the amounts of protein needed from various sources to maximize MPS, animal sources of proteins have huge advantages over plant sources of proteins. This is true even when those proteins are isolated.

well we know for sure that a vegan diet does not make you the worlds strongest man, because all the worlds top athletes would be vegan if it gave them a competitive advantage. They dont care about morals or flavor, if it means better performance they will always choose the better performance, they prioritize performance so much that so many athletes are willing to risk millions of dollars to cheat with illegal PEDs to get a slight edge against the competition, so if going vegan gave them an edge they'd all be lining up to do it.

Compounding that, deriving the relevant EAAs from non-animal sources would be wildly inefficient even at the consumer price per serve level.