I wouldn't call signal processing "narrow applicability." Signal processing is important for a wide range of computer science applications, for example any voic

I wouldn't call signal processing "narrow applicability." Signal processing is important for a wide range of computer science applications, for example any voice processing with regard to AI or security (think Siri!), and many programmers will at some point call FFT without really knowing what it is (happened to me twice this year already). Having read the FFT bits really helped to understand what it does. It also happens to be a really cool application of divide and conquer that was absolutely groundbreaking. So like from a practical, historical, and cleverness standpoints, it seems like a great thing to describe. I'm not sure it's important at all to remember how it works, but having some kind of idea of how it works seems valuable. And it probably just takes a lot of space because it's complicated. Haha.