I read though the article and the comments, and no one seems to think it's due to fraternities essentially being gangs. They act collectively to help everyone within the faction succeed while other people tend to be part of much smaller and less cohesive networks.
Much like humans beating out neanderthals who were individually more intelligent and stronger, but couldn't organize as well, frats bind allegiances in ways that casual friends rarely will go to the same lengths for.
Well, that's how a lot of colleges in the US and UK have historically worked. In the UK it was more explicit; if you were an aristocratic sort, you would send your children to a private boarding school where they would meet and befriend the children of your Peers of the Realm, and since Britain was a global empire back in those days, often the children of a similar upper class of people overseas. Prestigious universities functioned as an extension of that into young adulthood.
In the US today, it's less about class and more about money. It's not that your child grows up among the children of nobility, so much as the children of people who can and will spend 5 (or even sometimes 6!) figures a year on their kids' education and future. Things like 'legacy admissions' and a difficult-to-navigate application process keep prestigious institutions largely full of the well-off, and again, since these really are world-class educational institutions, that includes well-off individuals from around the world. I think that Greek organizations are just one common part of the system that persists more visibly after graduation, but it's really about getting to know broad network of as many powerful people as possible.
That sort of dynamic in education really stymies social mobility in general, though. It's like opportunity hoarding.
It’s still about class to an extent: source I was a legacy at PA Andover. Class is still an issue, but the definition has changed to include the acceptably upwardly mobile. The core is still some version of family continuity though.
> no one seems to think it's due to fraternities essentially being gangs.
Probably because the word "fraternity" already captures all of the features that overlap with gangs without bringing in a whole load of irrelevant connotations?
Fraternities seem to want to be so secretive about what they do and how they operate that it's helpful to use a different term that's more widely understood.
As for 'irrelevant connotations', I know you are saying that because of the implied violent and illegal behavior that takes place in a gang, but from the outside, it doesn't exactly appear that frats are immune to that either. It's actually quite amazing how cohesive the organizations can be once a woman accuses one of their members of sexual assault.
Much like humans beating out neanderthals who were individually more intelligent and stronger, but couldn't organize as well, frats bind allegiances in ways that casual friends rarely will go to the same lengths for.