I agree. Particularly because care in one garden will influence how it looks - versus care in another garden. If you have a kishu and itoigawa right next to each other, in the same garden, and you KNOW that one is a kishu and one is a itoigawa, you can tell them apart. But as far as visually confirming based appearance alone? It can't be done - or at least the best you could say is it "looks like" an itoigawa.
I purchased a large shimpaku from a well-know bonsai nursery on the west coast a number of years ago. It was buried out in the back in a sea of San Jose junipers - such that the owner was even surprised that it was out there after I dragged it out (it had been there for years). However it was not labeled, and other than knowing it is a shimpaku... no one will ever really know. It "looks like" an itoigawa - and I can bring my known itoigawas and put them right next to each other and they look identical. But "looking" is not the same as "knowing".