Why is an engines strength usually measured in maximum horsepower rather than torque?

Question

Why is an engines strength usually measured in maximum horsepower rather than torque?

Answer 1

horsepower is a function of torque.  In very simplified terms, torque is how much work you can do, horsepower is how fast you can do it.  You need to know how much work you can do before you can figure out how fast you can do it.

Answer 2

I guess one reason is that when at the edge of thier capabilities, cars stay at high rpms, where the peak horsepower usually is.  On the other hand, torque, usually peaks out at lower rpms.