I think part of the problem is that people selling seeds as F1s aren’t really selling F1s to begin with. Assuming you start with 2 parents that are fairly homozygous, you should actually get a lot of consistency in F1. F1 plants should show all of the dominant traits, and only “like” recessive traits.
But in the seed market, people call poly x poly F1, and then you’re mixing in a lot of heterozygous traits, which create children with both dominant and recessive traits. So this is probably what creates a spread in chemotypes, some of which have high THC.
@Sebring made a good informative post about this a while back:
With some, this might even be intentional. I remember reading arguments for and against the idea of “just cross elite with elite”. I think in clone world, pheno hunting a large set of mostly high THC seeds is not a bad thing. But if you’re selling seeds based on this process, it becomes pretty questionable what you’re actually selling your customers. 100 seeds creates 100 phenos, so in that context, are you even selling a strain?