When a breeder of a plant creates seeds, he or she hopefully is picking from many specimens, selecting the parent specimens with the desired traits. Strong stock crossed with strong stock hopefully creates strong seeds. The best breeding programs grow dozens or hundreds of parents to select the best stock from.
You, the OP, would be growing seeds where you have no idea whether the parents are strong/potent/high yielders/good tasters. They are just two random plants. You have no information to indicate that these plants are special, in any way. You'll get seeds, but you will have no idea of their worth. The odds are exceedingly good that they will be lower quality than the parents, and of lower quality than purchased seed. People use cuttings precisely because of this effect. Back in the day, we had to do this, because we had no other choice, and good results were rare. That's why we took cuttings from our gems and guarded them carefully.
I won't waste my growing time/efforts on unknown seed. I won't waste my time thinking my random mix will somehow be better than a breeder, who has stabilized lines, experience, and many potential parents to choose from. Ten bucks for a seed that will produce ounces or pounds of quality is pretty cheap.