"We" as in a total society or specifically as men do not stack any of these specific expectations on young girls. Young girls do this to each other. The influencers are girls and followed by girls. Instagram is girl territory and all the social gossip around it is girls.
They're not trying to win boys' approval, instead girls' approval.
Social ranking amidst young girls is natural behavior, what changed is that the limits of the physical world that kept it in check were removed, and now we see the fly-wheel effect.
Indeed, I am glad someone said this. The myopic GP analysis, characterizing young women as victims of murky cultural dynamics, is decades out of date at this point, and does not consider the complex real-world experiences and tremendous personal agency of these women. I think the supposed "mid-century traditionalists" have a keener appreciation of that agency.
To simplify the reasoning about this dynamic, I call it the duck lip effect.
At what point did "society" ask for duck lips? Where exactly did specifically men ask for it and actively select for it? If anything, they widely reject it. The expectation for duck lips does not exist, it was spontaneously fabricated by female influencers and that puts the idea and "expectation" in young girls' heads.
In other words, for as a long as we richly reward female influencers setting exactly the wrong example and being awful role models, this carries on.
I think if you put ten random women in a house for a week, you're going to get girl drama and pictures of duck lips. Just like if you put ten random men in a house for a week, you're going to get wrestling and videos of Jackass stunts.
They're not trying to win boys' approval, instead girls' approval.
Social ranking amidst young girls is natural behavior, what changed is that the limits of the physical world that kept it in check were removed, and now we see the fly-wheel effect.