In my experience teaching my friends and colleagues there are two ends of the learning spectrum--you can learn by example first or by theory first, or both, but the former is by far the lion's share of the population.

I've taught people where there's absolutely no way I can teach them a generalization unless it's rote--however they can get domain-specific knowledge and beat me over the head in their domain and teach me something about my generalization as well that I might have been missing.

The best way for me to teach calculus to most people is to walk around a room explaining concepts like velocity, speed, acceleration, and position. However, I personally would never learn it this way--I prefer Spivak, during my read through I learned more than I could ever learn in a class.

It's also my belief that most people aren't like me in the sense that they learn from example first. However, most people I know are like me so it's hard to realize how needed a textbook like this is and how huge it could be for the regular person to learn something like this.