I disagree even though math was my favourite subject in the school. I think I truly only enjoyed math and physics. They were the only subjects I felt like I could actually problem solve and not have to memorise facts I can't relate to or do not know what to do with. But really the maths taught at school also seemed like not really related to creativity, but more like memorise this formula => rote practice with this formula, on and on from there. While if it was about game dev, or programming, it would've been more about learning to problem solve in a bit more creative ways.
> Every good game designer cribs extensively from history and literature.
This highly depends on the game, the designer and multitude of different factors. I despised history when I was in school, but now that I've got older I've grown natural interest towards it which has allowed me to learn it with magnitudes higher effectiveness compared to when I was a child. Without my own life, and trying my own things, I didn't have interest in history, because I hadn't lived, so I didn't have anything to relate it to. I was clueless about people's motivations in history. It was just a compilation of random facts that I was forced to learn. Understanding people, their motivations, goals is the most important part of history, and without understanding those aspects, I just don't understand how I could be interested in history enough to not think of it as random facts.