Beg to differ. There are many instances of sex-linked traits passed from one sex that is expressed in the opposite-sex progeny. In humans, male-pattern baldness is the well-known example. Again, having only mapped the cannabis genome in the last couple of years, the state of the science here is in its infancy, and your statement that "males don't matter" is based more on ideology than biology. We simply don't know what alleles code for what traits in cannabis, yet.
You seem to know enough about genetics and evolution to wrap your head around this. Breeder selection is the primary evolutionary pressure placed on drug cannabis. So, what is a "fully female" plant? How does one select for "full femaleness"? Is that REALLY what a feminized seed breeder is selecting for?
No, s/he is not. The feminized breeder selects parent stock PRIMARILY based on those individuals WHICH WILL EXPRESS INTERSEXUALITY when exposed to stress, such as chemicals. Therefore, the feminized breeder intentionally, and as a PRIMARY trait, selects for intersexual expression. S/he may select carefully, for those individuals who tend to express intersex traits only under severe stress, but select he does. Any truly "fully female" individuals which do not express intersexual traits under extreme stress will be culled from the program by their very virtue of being unable to form male flowers with viable pollen. Feminizers aren't selecting for "fully female" plants, they are culling them, because they won't "flip."
Therefore, any feminized plant breeding program, by its very nature, will select and breed for individuals with an ever-increasing frequency of intersexual expression in the offspring, by the very nature of the breeder's selection - conscious or unconscious.
I've heard this "fully female" argument from feminizers for years. It's bunk pure and simple. Sexuality, in animals and plants, is expressed along a spectrum. It is only binary at the chromosomal level. Chemicals don't change genes, as you said, they simply change the level of environmental stress, which the plant responds to based on its genotype. Those plants with genotypes that favor intersexual expression form pollen sacs. Only those plants which form pollen sacs get feminized. Feminized breeders select for hermaphrodism, plain and simple.