Another factor is homogeneity of the offspring: parent lines are very much homozygous. If one parent line is AA at one locus, and the other line is aa at the same locus, the children will all have Aa. Meaning they have both versions of the gene (which is usually good, especially in immunity and health) and all have the same status. This means you can produce a couple of hundred piglets grow to the same size in the same time which makes processing and marketing them easier and cheaper.
Another factor is that some breeding goals are mutually exclusive. Piglets for example drink milk from the mother, which means she must have good milk production and other fertility related features, whereas the father can be bred more for muscle growth.
And then there are other weird tricks breeders can pull. I believe in chicken there are experiments with hybrids that hatch in different colors relating to their sex, or don't hatch at all if they are the "wrong" sex.
Hybrids outperform single lines (breeds, etc) on most metrics of interest. And they are homogeneous in growth, size and body composition (animals). Which matters for industrial processing and marketing. And for the price consumers have to pay.
The current agricultural mass production would just not be possible without such hybrid breeding programs. So the OSSI will need to offer seeds from similar breeding programs. There are always lines/breeds which are not hybrid-bred, but the market for that produce is limited.
Higher performance also means less animals tortured, less land and water used to feed the same number of Humans. From a global perspective plant and animal breeding has to become more professional, not less.
As far as I have understood it, the OSSI wants to professionalize the breeding efforts of (non-breeding-company) farmers and small scale breeding companies. Much like many open source projects got professionalized through forming organizations and legal entities.
There is a concept called hybrid breeding, both for animals and plants. The "final" product, the seed for the farmer, the piglet raised for mass production, is bred from two parent lines, one for the male part, one for the female. Both are relatively inbred so they are mostly homocygotic. Their offspring, because of Mendelian genetics, is mostly heterocygotic, but very homegeneous, which is a great thing, industrially speaking.
However, a farmer can't just raise those piglets and breed them on his own. Not because of patents or licenses, but just because the offspring would be all over the map, genetically. And probably less profitable. The breeding companies need a complicated system to develop these lines and provide their customers with the best seed/livestock. That takes a lot of money and effort.