Only on MN have I ever encountered this mythical Western preference for girls.
I have encountered it a lot. Because I move in circles where people are able to express a preference and have that taken into account when being matched with a child and so will say what they want.
Mostly people have no choice and therefore keep their mouth shut because they don't actually have a choice and they look pretty silly when they have a child of the opposite sex to the one they've told everyone they want.
People say what they think online because they are anonymous.
The fact that there is a gender preference for girls in the west at the moment doesn't mean:
1 - that every person wants a girl
2 - that feminism has gone too far
3 - that men are the oppressed gender
It doesn't even mean anything positive for girls/women.
When I adopted DS there were 6 boys and 2 girls (both with moderate health issues) being adopted at the same time in the same place. There were originally equal (roughly) numbers of boys and girls available and those were the only girls left available for adoption in the 0-2 age group and when they left there were no girls waiting to be adopted. There were several healthy boys under two but as they were boys and many were Asian they are the most difficult to place.
These were all western families adopting. It is of course possible that other factors are in play when its adoption - there's a theory that men find it easier to accept a non-genetically related girl than boy for example. But I have seen with my own eyes time and time again that people will wait longer for a less healthy girl when there are healthy boys ready to be placed.
But you can't argue with the statistics that even in countries where more boys than girls are available for adoption (eg Russia) there is still more demand for girls despite longer waiting times. (Caveat most of the statistics are American but from experience the UK isn't much different)
I apply no value judgement to this, it is as it is. But if you don't think there is a trend in the West to prefer girl children over boys then I think you've never been in a room full of people who are able to choose and seen for yourself how many (at least initially) want a girl.