The Heidelberg freemasonry
It is easy to mock as macho idiots the Heidelberg students of yore who duelled with swords for the sole purpose of acquiring a facial scar. But has anyone studied the question whether students with scars got laid more often than students without scars? If this is the case, it would make duelling an eminently rational activity.
It is also rational to desire a job. Once an arbitrary freemasonry is in place, whereby older men with scars preferentially appoint and promote younger men with scars, then acquiring a scar becomes a part of the process of qualifying oneself for a career, more important than mere scholastic grades. Were the entire economic future of female students to be dependent on duelling to acquire facial scars, they would take up the sabres too; after all, women have done much worse to themselves in order to land husbands.