That's like saying I can ride my AL mountain bike to work and ride my steel race bike and the ride takes much less time on the steel bike. Steel must be faster than AL. My AL mountain bike is also a Much cushier ride, so steel must be harsher too... You can design a bike to have whatever qualities you want out of AL, steel, or carbon.
My touring bike is AL, and I've put thousands of miles on it. It's definitely not harsh and doesn't fatigue my hands or arms in the least. I actually did about a thousand miles on it with no bar tape because I broke a brake lever and didn't bother putting on new bar tape until I got home from the tour.