Jim . . .
You're right, of course -- but look at the vast differences in how the two markets are shopped (and who shops them) to place my point into proper perspective.
The best Japanese koi will (by and large) will be steered by breeders, dealers and brokers into the hands of hobbyists (with mud pond access) that have a reasonable chance to not only maintain them, but grow them on to reach their genetic potential.
Do our domestic breeders steer their top koi to our top dealers and top hobbyists? No.
Do Nishikigoi of Niigata, EnKoi, Genki, Champion, Kerin, &/etc. aggressively shop and stock the domestics so that our top hobbyists can select top grade domestic tosai? No.
Because the same collaborative networks and relationships do not exist in our domestic market, the odds of a domestic GC tosai being purchased and grown on by a GC quality hobbyist are infintesimal.
So it don't much matter if our domestic breeders produce the odd GC calibre tosai, odds are it ain't never gonna make it to The Show.