The more variables in a system the more difficult it is to design. Riding a bike is an easy system to understand. The physical world is constant. People have muscular-skeletal systems. Bikes were made to fit the human form and so riding a bike is easy enough that children learn every day. That's one of the few tidy systems. Most other systems are more complex and offer interacting parts that feedback onto each other.

Rather than reading about this I got to live it in one of the first CAS identified: weather. In September 2019 Hurricane Dorian inflicted more damage on the Bahamian Islands than any storm before. I lived in Central Florida and began to prepare for a potential storm as several models indicated it would come in our direction. Ultimately the storm didn't but only because of all the interacting elements.

Days after the storm passed Florida, splashing only the Atlantic beaches, a Miami weatherman explained the weather in terms of a CAS. Dorian damaged the Bahamas because of a low-pressure system to the north which was slow-moving because of changing the weather to its northwest. It was the weather in the Northern American Plains that nudged Dorian one way or the other. The combination of pressure, temperature, and other factors in Kansas changed the storm in Florida.

Teams are also CAS. Some people make everyone around them better, some sour the spirit. Markets are also CAS. It's buyers and sellers that interact in ways with knock-on effects that make predictions difficult. Within CAS base rates are especially helpful. No matter what our optimism, effort, and intelligence our individual (or group) effects won't matter much with the many interacting elements.