It makes much more sense when a generation boundary is marked by some sort of significant societal shift. Like Boomers are people born after WWII ended. I guess Gen X kinda makes sense being defined as a generation that grew up after the civil rights act and the establishment of rock & roll. But it seems like there should also be something between that and the internet, because as you say there’s a difference in late Gen X. Maybe the advent of video games should be a cutoff. Someone who grew up with video games and VCRs in the 80s has a pretty different experience from someone who grew up in the 70s.