Sorry, but that's just tripe. Whether imported or native any subspecies will breed true given sufficient saturation.
Saturation is roughly equivalent to vast majority.What has the "vast majority' got to do with breeding true ? Either they're pure breeding or they're not.
Bit of a waste of time discussing this with you if you're posting contradictory nonsense and throwing in the odd Oberusel to try and show some substance to your empty words.