Crosses will sometimes produce infertile offspring.
This is particularly true when crossing two peppers of different & semi-incompatible species (some pepper species will cross
readily with each other, some combinations
will cross but typically produce infertile offspring, and some combinations
will not cross at all! )
Also, it is possible to chemically treat a plant to produce offspring with
double the normal amount of chromosomes (tetraploid plants). If you cross one of these guys with a normal plant, the offspring will have an odd # of chromosomes (tripoids), which I believe will also render them infertile.
For a seed company that sells to commercial farmers, there is an obvious benefit to creating seeds that produce productive plants, but where saved seeds are either different or non-viable, so that the farmer has to keep buying new seeds from you every year!