I might have asked this before, I don't remember.... so in my limited understanding of neural networks and machine learning, the basic idea is that each generation, the "best" survive and move on. So in the next generation, more of the population will be more similar to that previous best, giving a better chance to reach a new best.
I've seen videos on training AI to play Mario, for example, and there, the "best" is defined as "got farthest to the right in the stage". On an AI learning to play Tetris, it knows it did well if it survived for a longer time, or more total piece drops, or total lines cleared, etc.
But with generating Dominion or MTG cards, how is "best" defined? What criteria is used to determine which members of the population survive to the next generation? If it is "similarity to existing cards", then wouldn't the AI eventually just generate exact existing cards repeatedly forever? I wouldn't think it would even take very many generations for it to arrive at "hey, if I just copy this existing card word-for-word, I end up with a result that gives me a perfect score".
Or, does training an AI to generate cards or other text in this way follow a different fundamental principle from training an AI to do better in a video game?