I think it's more that the person that made the meme is a neuro-divergent male and they are looking at girl groups that aren't. It's more common for both male and female neuro-divergent groups to have broad age ranges, as personality compatibility is a much more important friendship metric to us than what age someone currently is. Where as for people that can be friends with a large percentage of the people they meet, they tend to hit their quota of friends while still in places where everyone tends to be the same age range.

Also the numbers are pulled from some other meme, I assume. As pretty much every single one is wrong in this context. Most of those girls are unfortunately, but unsurprisingly, in the 16-18 range, with a few a bit younger, or alot younger.