this comes from old feminizing methods of long ago, that are now quite out of date. today we use hormones
the incidence rate is exactly the same. and based on the parents genetics
I've heard of some seed makers still using stress to induce it. This will produce plants more prone to herming from stress no question. But yeah, otherwise. Most people have learned from the past.
Some strain are more prone than others, Almost any God bud crosses I have ever grown (CBD GOD, OH God, ...) and some other from Jordan almost always hermi the way I grow them while a lot of my other strains dont. I find when I get most hermiing there is a new light leak I didnt know about or some other possible stressing factors. Anyhow, his strains have always been some of the best I have grown and often the offspring dont hermi... Naturally I think if the commercial breeders of today stop using males altogether we will run into problems down the road. I always encourage closet growers to flower their best males (often means the latest one to show sex but not necessarily the runtiest) and make regular seeds. I do get a bit freaked out seeing where the seed bank industrie is going with mostly fem seeds or auto seeds. I wont hesitate to grow seeds from hermies but I make a point of creating regular seeds every now and again and not get them mixed up with feminized or hermiing genetics.
I think it's important to keep the males involved as well, but for different reasons. You will never ever use the male half of the genome if you are growing cannabis for flowers to smoke. It really doesn't make a difference at all. You can preserve the female half of a male using females (from the same line) just as easily.
However the male half of the genome also contains other important traits and the male plants themselves can have great utility (the biggest and baddest plants for me are always males... the ones that seem to produce the most biomass) and I think it's important to not toss that aside.
It's also important for the lines we love - if they ever need to be set free in the wild that they can easily reproduce themselves. Males make that happen.
The other thing that is really a problem in the cannabis industry is how lines are preserved. I see so often people using 2 or 3 plants and calling the job done... it doesn't work like that unless you are preserving a line that's perfectly homogenous and they do not exist in the world of cannabis (well, maybe in Chimera's lab but that's another story).
If you are trying to save a line make sure you save it using a reasonable number of plants. Hypothetically you should get a complete preservation in 20 or so but you probably want to run more because hypothetics are just that and sometimes you get unlucky.
This is an actual major problem IMO.