This the way I see it. Pizza has low vulnerability because the ingredients all work by themselves. You can double or half the amount of an ingredient like the cheese or the meat or the sauce and it won’t affect the other ingredients.
But cake is about proportions. You have to get the right amount of ingredients compared to each other. And that means if you screw up one ingredient, you’ve throw off the entire cake.
To use an analogy from electricity, the ingredients in pizza work in parallel and the ingredients in cake work in series.