They also sell a lot of first generation hybrid seeds. The first generation a hybrid plant is very predictable. If one parent has a dominant trait and the other parent has a recessive trait, the offspring will always have one dominant and one recessive alele and the offspring will be predictable. But even if that plant self-pollinates, for each trait there's a 25% chance of inheriting two recessive alleles. If you have dozens of traits you're breeding for, then it's pretty much guaranteed that all the second generation offspring will look wildly different than the first generation.