I've no idea, I don't play Magic nor am I interested in doing so. What Magic, or any other product, does is completely irrelevant. I have also not said that you can't play this game without 3 copies either. That is also not the point.
having at least 3x (if you want 6x, go for it, that's a separate issue as well) is essential if you want to play the game seriously because you will need those choices to hand. I will not countenance any game that operates in that way, whether it's 3x or 4x or whatever, that doesn't give you any way to get those cards but to buy multiple copies of the core set like this, especially when that means buying increasing amounts of cards you won't use. It's not even as if you could trade for these cards. This was a huge oversight and I would love to know what FFG's reasoning on this is.