In olden times, gyrocopters were an important part of experimental aviation, starting with I. Bensen, K. Brock and last year, the CarterCopter. There were a few brands of commercially made gyro's present. FAA does not yet certify gyrocopters except as experimental. I could not find any forums on them. They are sold as certified aircraft in most countries in the world, even Canada, Europe and U.K.

What might be the reasons for this?