Turns out that’s a bad way to structure a society and being hyper individualistic just ends up in your society collapsing.
The Black Death was pretty horrible and yet European society still exists.
The Black Plague is not even a cold compared to what we can engineer.
Really though I can’t imagine what you think this pedantic obsession with whether or not everyone gets blown up immediately is adding to the conversation.
We'd be 10 thousand not 10 billion and life would suck but we would survive. And the fallout would clear within a few decades or centuries.
10 000 people is not nearly enough for a modern division of labour - we'd be reverted back to prehistoric technology levels within a generation, with a bonus of fallout and absolute climate dysfunction. Given a sufficiently destructive nuclear exchange literally every single human could die.
"Societal cohesion" doesn't do too much to help us survive crop failures and wet bulb temperatures over 35C.
Aside from that, I think you might misunderstand your causal arrows a bit. It is fair more likely that massive industrialization and late state capitalism led to a society that valued the individual over the social unit, rather than that a sudden desire to be individuals sprung up in people's hearts and made a mess of the world.
All that where created by an individualistic approach. Party now and let future generations deal with the dirt.
How so? TFA attributes this modern alienation to changes in the American family structure that took place in the last half of the 20th century. All three of the threats the person you’re responding to listed, nuclear war, (modern) biological warfare, and climate change, were developed or essentially locked in in our society prior to the last half of the 20th century – largely by people born before or right around the end of the 19th century, who were presumably much more attuned to this “dutiful family obligation” mindset, since those are the very people TFA is contrasting these post-1950 changes against.
The plain history of these developments would seem to argue that post-1950 societal changes had nothing whatsoever to do with these threats, unless you’re arguing that the effect preceded the cause.
Let me guess: you are not a parent
The person you're responding to is referring to how societies worked since time immemorial, prior to the advent of such strong individualism.
One difference now is freely available contraception and a much lower birthrate, combined with more economic stability. (At least for the boomer gen.)
When parents have two children and both are estranged, it's a tragedy. When parents had ten children, five of them made it to adulthood, and two decided to leave, it was acceptable attrition.
The other difference is the absence of extended family and friends who can step in with childcare help. So parents + kids going through adolescence under the same roof becomes a pressure cooker. No one gets much of a break for 4-8 years.
Alternate take on that human universal: your parents had unprotected sex and fulfilled their obligation to raise the offspring produced to adulthood, this obliges you to nothing.
I'm not saying this means everyone should estrange their parents, but the idea that a child has any obligation to their parents for raising them seems misguided at best and damaging at worst, imo. Any attachment between children and parents should be due to mutual feelings of love and respect, like any other relationship - if those are absent on one side, why should the other suffer a relationship with people who they would otherwise remove from their friend group?
(Note that I have a good relationship with my parents, so this isn't coming from a place of personal pain, but rather a dislike for the idea that two humans procreating and fulfilling their obligation to the offspring that comes of it should impose any obligation whatsoever upon that offspring.)
EDIT: I should clarify that I do believe that parents who went above and beyond that obligation to show their children love and respect and receive nothing in return have a right to be upset - however, what about situations where a parent thought they were doing the right thing (based on how they were raised, religious briefs, parenting advice from a friend or magazine, etc.) but the thing they were doing was actually harmful? There's a lot of nuance in this, but I think that a blanket "honor thy father and thy mother [out of obligation]" is a bad idea.