This is a form of grooming (like primates). Here is a video for you, where your question is answered very comprehensively. You
Oh! What a wonderful question!))))
I can’t answer for those girls who don’t care who they put pressure on. So below will be purely my opinion, maybe someone else has the same.
First, it's a matter of aesthetics. Well, I don't like to see on a person enlarged pores with a black dot on top or small tubercles of fatty glands. Since he himself is not always convenient to squeeze them out, I am happy to take this occupation into my own hands.
Secondly, a certain intimacy of the process, which means a very high degree of closeness and trust on both sides.
Third, excitement! Sometimes you crush some ordinary little pimple, and then .... And there is such a "hidden potential"! It is interesting to find such a pimple every time.
And fourth, the process itself fascinates. From and to.
Something like this.
This is some awful obsessive disorder! I never understood it. It’s even difficult for me to imagine that I did it on my own initiative. If only asked or necessary, it seems like to glue the cut. 100% obsession!
And by the way, girls with such an obsession crush everything that is horrible and for anyone - friends, girlfriends, relatives ....
This is probably a form of grooming. Well, I mean, grooming is typical for a person's closest relatives, so you can expect it, in one form or another.
Judging by the prevalence, irrationality, persistence and even some obsessiveness of such behavior, one can assume that that it really is rather instinctive.
It is not clear, however, why it applies more to girls.
I have no logical explanation, but it's really cool, especially if you press black dots.
I don't press myself either, because there are no acne, but I like the process of "pressure".