See, I kinda see it the other way. Generational demarcations used to be cultural and thus geographically determined back when different places had different media. Now we all have the same garbage social media, so since the 2000s it makes sense that we’re all on the same boat made of crap and hate.
For example, my parents had a moon landing, but it looked, sounded different and meant very different things. Also for example, I had no idea what Oregon Trail was or what it was about until the Internet told me it was a staple of US computer classes. If you think about it for a few seconds it may be no surprise that my equivalent was some combination of drawing dicks in LOGO, Defender of the Crown and Saboteur II.
We have local names for people born in the late 70s to mid 90s, too. After that we just use the US-designed universal names, though.
Right. That’s my point, though. Depending on where you are in the world and how joined at the hip with the US you are culturally this particular set will start making sense at a different point. In some cases not at all.
Where I am millenials are the first that definitely sync up. Up until GenX we are in a completely different set. I bet in other parts of the world even with how fully online we all are even then it doesn’t click.