I can't speak for them, but some of the proponents of forced-outbreeding (i.e., eugenics) may have a hidden agenda of trying to garner mainstream acceptance of their animal-f-cking ways. You know, "hey the reason I like f-cking animals (all animals, not just mammals) is to maximize the population's gene variability, uber-population, so we can avoid extinction."
It used to be said that the idea of a beneficial recessive trait was a joke, but sometimes people just talk instead of thinking.
Sometimes, and sometimes narrowing the gene pool leaves the population more able to deal with "disasters".
Touting a university degree and calling your opponents Hitler is what it is, but it's not the same as supporting your assertions with evidence, and around here, people are said to be required to support their assertions with evidence.