The pure culture process (pretty much all the stuff invented by Pasteur) is based on isolating a single living cell of yeast and then growing a culture of its genetic clones by natural budding (our brewer yeast lost ability to reproduce by other means some centuries ago). This ensures that chances of mutation are small and there are no other organisms in the culture. It also rejuvenates yeast, as growth conditions in this process are much more favorable and pleasant, so that cells generation can build large energy reserves inside. This is surprisingly low tech, could be done at home (lol that’s what I do), but it takes certain discipline, even more cleaning than brewing.

As of killing feature, I’m not sure exactly what it is, but for some lines they report an ability to efficiently inhibit the activity of competing organisms by means others than just outcompeting them in multiplication and consumption of nutrients. These lines should be better for introducing uncooked stuff to fermentation (fruits, berries, spices, maybe raw honey), although I’d say that really vigorous yeast can outcompete almost anything under common conditions, maybe save for really high pitch rate of acetobacter. I don’t pay much attention to this feature really, but it’s a curiosity IMO.