Another major sticking point when it comes to "eradicating genetic disability" is what exactly qualifies as a disability; realistically the idea of "disability" is a human invention in a lot of cases.
A specific example they sometimes use in biology classes is
sickle cell anemia. It's a disorder that, as its name suggests, causes deformation of red blood cells which compromises their ability to carry oxygen. It's also known to be a disease that's more common among those of African descent.
So obviously that's just a flaw and evidence of genetic inferiority, right? We should totally get rid of that.
Thing is those adapted to live in Africa have it more often for a very good reason: it turns out that sickle cell anemia
is also a major resistance factor against malaria. So what would at first glance appear to be a genetic disorder, in fact, confers a selective advantage under other circumstances.
And that's what a lot of this shit comes down to. Humans aren't nearly as good at figuring out what should and shouldn't be as they like to think, and whether we're talking biology or law or w/e it may be, trying to shove one's hands in there and play god winds up backfiring far more often than not.
So even if eugenics was an ok idea in theory (which is highly debatable; to direct the human genome life would have to have an objective universally agreed upon goal, which it doesn't), humans could never execute it on themselves. We're too fallible and prone to bias.