I clearly walked into the middle of something I'm missing context on. Baby Boomers didn't name themselves, academics older than them did because the postwar baby boom, mass media, and prosperity brought about a markedly different generation than what had been the norm before. And since academia was growing large/widespread enough to study that particular phenomenon, they applied it retroactively to other generations. If a generation was likely to name themselves, it was probably the Greatest Generation, tbh, though I'm just guessing based off of when studying generation theory started appealing to historians.
It's not, and was never meant to be, a prescriptive monolithic summation of an entire group, it's an aggregate descriptor. What age you were at experiencing past historical events shapes, in aggregate, how the people respond to future events. I don't see that as surprising. How much of outrage against a prospective war with Iran in this thread derived from people ITT who had grown up watching forever wars in Iraq and Afghanistan end with nothing but death/destruction? Certainly a lot. And their perspective would be different from someone who was of military age during the Gulf War. And theirs would be different from those who grew up during Vietnam. That's how people process current events, leveraging it against how past experience effected their outlook.