Firstly, what is hypergamy? Hypergamy is the act of dating and marrying someone of a higher attractiveness/social status to themselves. Now how does compliments encourage this? Well women compliment each other (strictly talking about compliments on looks here) for either 3 reasons one is they want to make the recipient of the compliment feel better about themselves even if a woman is incredibly by "society's" standards overweight they may still call them slim and pretty, these compliments are too make her feel better about herself and make her feel good as women like supporting each other. The other reason is more subtle and harder to hear. When we assign value to something like a card if a group of people think its valuable it suddenly shoots up in how much its worth and how much you can get with it, this is what's happening when a group of women compliment another woman. for one their intrinsic value in the dating market goes up as they feel wanted as people compliment them and they themselves think they deserve more because they are so "pretty" and " stunning". Others who may not even see the person whos being complimented as pretty but because of peer pressure they now do. This more and others I'm talking about is a guy of a higher calibre, for one that's someone better looking or higher social status and wealth. Compliments are for one to make the person saying them feel better because they now they think they're nice and to allow others to reach someone higher and date up. Other reasons for compliments are for example the woman complimenting someone else might look like them thus they want the idea of a person that looks like them to be deemed pretty so they'll give the compliment to feel greater self worth. That's about it, often guys don't do this because guys don't really have much opportunities to date up and aren't as conscious if they do date up so they don't need reinforcements through compliments to feel enough to date a person above them in the dating market. Also, yes I'm aware compliments can be sincere and you may not think this has the effect I'm talking about, but it does. And no I'm not against compliments, it happens regardless of what I think.