Sort of. Without random variation we are really limiting our potential, and will be relying heavily on genetic analysis and reproductive control via law to prevent what will become, at least initially, increasingly common recessive diseases.

See purebred dogs.

They absolutely are wrong from a scientific perspective.

Quick sidetrack: There’s a lot of misunderstanding about what people of the time meant by eugenics, because it’s rightly been associated with Nazis. That’s just where eugenics inevitably winds up, and it can’t and shouldn’t be uncoupled from that history. But prior to that it was considered a progressive cause, because the ideal was to reduce or eliminate human suffering by stopping disabled people, criminals, and other people considered undesirable from having children and thus preventing more disabled people, criminals, etc from being born to begin with.

But that’s not how genetics or criminality works. Most disabled people aren’t born with their disabilities, and those that are aren’t necessarily inherited from their parents; with deaf people for example, the vast majority have two hearing parents and they’re deaf due to a de novo mutation. If no deaf person has children ever again you would still have roughly the same number of deaf people in the world.

In addition from a genetics perspective, eliminating a trait from the gene pool can have weird, unexpected effects downstream. Maybe once you remove a lot of these things you think are undesirable at the same time, it causes a collapse of something else you didn’t even know was related.

You can't escape the inter-connectedness of human body systems. Improve something somewhere, something else gets changed too. This is why being a doctor is so hard.

So, it's only true from a 19th century understanding of science. Which a lot of people admittedly prefer, because of how simplistic it was. It's a lot easier to feel like you understand things if you just ignore all the complex and hard parts.

I see the main issue with anything theoretically "sound" is that humans are making the decisions. Human bias, and forgive the drama, make everything worse including science.

Look at what we've done with the environment, introducing invasive species, pet-breeding, colonialism destroying literally tens-of-thousand of years of culture and people because we thought we were "right".

There's an inherent arrogance that's led us into this mess and only recently some have thought to ask "hey, these people and culture have lived and thrived without disrupting the natural ecosystems, let alone cause measurable changes to the climate - maybe they're experts in how to survive and nurture this place?

People will use whatever justification the can readily grab to do incredible destructive things and forgo responsibility by referring to science or religion alike. We can do better.