The amount of sheer working memory required to be a good programmer is absolutely ridiculous. As you start moving on to creating more complex programs that actually need to be able to do something useful, the amount of information you need to cycle through your head becomes crazy; Not to mention, you also need extensive math knowledge. Since WM is so highly correlated with IQ, I'd argue that CS requires the highest IQ to thrive. I've seen people do constant all-nighters to keep up, have mental breakdowns, and even quit to major in math due to it's difficulty.

I understand that CS Majors do not have the highest IQ's, as shown in many info-graphics, but this is different from necessarily requiring the highest IQ; It's easily possible that the reason math or philosophy majors have higher IQ's on average is because simply higher IQ people are more interested in those things on average.