I disagree with the claim that generations are not a thing.
Let's make this the following proposition: "generations" are a thing.
This might be somewhat subtle: "generations" is indeed a thing, but not in the sense that the concept leads to further insights by improving correspondence with reality.
Ironically, you actually provided evidence for this by your attempt at explaining why "generations" are a thing by not referring even once to "generations" when giving multiple examples how cohorts, or groups of consecutive cohorts, are exposed to external events unique to them and the effects on them.
Your exposition in no way requires the concept of "generations", nor does it indicate that there is anything to be gained from the introduction of a metaphor ("generations").
In context, "generations" does not provide any analytical advantage but what it does is to feed into our desire of categorizing complex issues in order to be able to deal with them on a metaphorical level, which, in turn, satisfies our need for being able to use heuristics in order to deal with an overly complex universe.
One might ask why "generations" is a problematic concept. The answer is that it allows consolidation of various characteristics with a comparatively higher frequency in the population of interest, solidify these characteristics as permanent (attached to a "generation") and subsequently project them on individuals identifiable as members of that group ("generations" in this case).
So "generations" is indeed a thing in this context because it does act as a lens that allows projection of supposed characteristics on individuals causing all kinds of problems.
Of course, in the case of "generations", all this appears rather benign but is anything but.
In fact, I'm only taking the time to write this because it is a much larger issue than it first appears, up to, but not limited to, persecution and genocide.
Although my post could not by any means a comprehensive treatment of the issue, but it could serve as a kind of Swiss army knife for decoding the logical structure of a whole lot of dangerous BS out there (mostly right wing propaganda but not limited to it. Look for the patterns and it will quickly become second nature and you won't be able to unsee it).
(I don't know if the poster who brought the subject of the difficulty inherent in mapping "generations" on long historical sequences of relevant events is aware of the size of the bite he took out of the metaphysical apple. It certainly is big enough to choke on.)
So here is the remainder of your post and it talks about exposures, attitudes and, most importantly, you use "probably", "might" etc., indicating that we are looking at probabilities and frequencies of particular characteristics in a defined population.
Keep in mind that we are dealing strictly with descriptive statistics of snapshots in time and that there are no assertions of truth beyond an estimation of the probability of obtaining similar results in the long run here (frequentist statistics).
I just want to be clear, the issue is not that there is an argument about if exposure to historical events changes attitudes etc., that is obviously true, but that there is no need to introduce "generations" as it does not lead to any further insights.
Rather, reifying, accepting and utilizing the concept of "generations" is simply a particular instance of opening the door to stereotyping, discrimination and, under the right circumstances, even genocide:
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There may not be a sharp, easily demarcated line, but people born in different decades spent their formative years in vastly different environments that shaped their personalities en masse.
If you were born in the 1920s or 30s, your formative experiences were of deprivation and community reliance, and as an adult you probably worked in a physical job. Many, many males served in WW2. You listened to jazz or gospel. You prioritized frugality, stability, and community. And if white, you were racist.
If you were born in the 1940s or 50s, you probably spent a large percentage of your free time in front of a television, and maybe you worked in an office for a service industry company. You might have attempted to avoid military service. You listened to rock-n-roll, R&B, or early pop music. You prioritized self-expression early in life, and money making and consumption later in life.
If you were born in the 70s or the 80s you probably spent much of your youth in front of a suitcase-like desktop computer or playing video games on the family TV, you too probably worked in an office for a service industry company. You listened to 80s pop, grunge, and especially rap. You prioritized being entertained. You spent your prime earning years bouncing from economic crisis to economic crisis, from 2000 to 2007 to 2020, and now you own crypto out of cynicism, techno-opportunism, and the idea you can get off the roller coaster.
If you were born in the 90s or oughts, you might have received an ipad or cell phone as a small child or teen, and spent more time doing that than any previous generation had ever spent on electronics. You were the first generation to not play outside very often, or roam your neighborhood, as your "stranger danger" parents felt the need to shelter you, and so they encouraged you to play on electronic devices instead. You reached maturity in a world where housing was unaffordable even for wealthy professionals, where the internet was the only source of current information you were aware of, and where sending genetalia pics and making racial jokes was the norm. Your defining generational experience was the anxiety of isolation of the 2020-2022 pandemic, which will cause issues later in life.
Do we really think people plucked from each of these cohorts, at the age of let's say, 25, really thought about the world in the same way, worried about the same issues, took pride in the same things (e.g. beating polio as a community, owning a nice car, having over a thousand followers), prioritized the same goals in life (e.g. having kids, owning a china cabinet, being part of an organized community, etc)? And do we think if we used our time machine and gathered these 25 year olds together, that they would be indistinguishable from one another?
