We do make generalizations about all the categories you mentioned. Some are harmless some are hurtful. This doesn't mean that demographics are irrelevant or that characteristics are randomly distributed. We are influenced dramatically by the environment we grow up in and nothing is quite so stable as the past. So, your exceptions do not discount the rule.
I'll take my generation vs gen Z as an example. I clearly remember 9/11, blowing NES cartridges to get my games to work, rewinding video tapes, making phone calls to friends on a shared line using a corded phone, having to listen to a radio station for 3 hours to hear the one song I liked and then rush to hit record so I could save it for replay, and on and on. I cannot share these experiences with gen Z. They won't ever have that. I can talk about it but it's just like a Boomer telling me about going to Woodstock or making 10 cents an hour bagging groceries, or dodging minefields in Vietnam, or using punch cards to program. Sure I can hear those stories and be amused, shocked or whatever by them...but I'll never know precisely what it was like to go through all that, with the mood of the time.
I'll take my generation vs gen Z as an example. I clearly remember 9/11, blowing NES cartridges to get my games to work, rewinding video tapes, making phone calls to friends on a shared line using a corded phone, having to listen to a radio station for 3 hours to hear the one song I liked and then rush to hit record so I could save it for replay, and on and on. I cannot share these experiences with gen Z. They won't ever have that. I can talk about it but it's just like a Boomer telling me about going to Woodstock or making 10 cents an hour bagging groceries, or dodging minefields in Vietnam, or using punch cards to program. Sure I can hear those stories and be amused, shocked or whatever by them...but I'll never know precisely what it was like to go through all that, with the mood of the time.