Well, I wouldn't say that.... AMD's architecture does make them harder to go to really high clock speed (I do believe it is a heat problem), but at the same time, IMO they don't have to. They have a smarter architecture that allows them to run much more efficient than Intel's cpus, so even with lower clock speed, they can still beat Intel cpus that are 300 - 400 mhz higher. This is especially true with floating point performances such as rendering operations.
Clock speed /= performance!! Its like comparing cars' performance only by their horsepower. There are other considerations, torque, weight, gear ratios, aerodynamics... and many more. Hopefully, more people will realize the truth about these comparisons and don't buy into Intel's "higher clock speed = better scheme".