Except it is in their genes to hibernate and not eat well for months. You are comparing a natural fish that has been surviving in frozen ponds 1/3 of the year for centuries (if not longer) with a man-made hybrid that only knows the constant feeding and water quality that human give the fish. They aren't comparable in those terms.
YES ITS IN THEIR GENES. RIGHT? YOU JUST PROVED MY POINT!!! So they get a better outcome even if the care isnt "good" or "ideal" in our eyes correct? We would rather have them in nice temps and feed them year around yet they are dulled out because and no amount of carotenoid astaxanthin can compensate the genetics. Subjecting them to the harsh conditions is made for them to achieve their full potential while US koi only get around 90% of their potential.