Actually I've been sort of adding them for colleges ... if they can be verified which can be tough.  Usually they advertise their symbols on their building so it is mappable.   Unfortunately there isn't a real standard to them, some people tag amenity=social_centre, and now I'm not even sure I should but I have in the past tagged amenity=fraternity (or sorority) which again doesn't mesh with other tagging systems.  So I don't know, might be room for discussion.  Closing for now unless other discussion is desired?
https://wiki.openstreetmap.org/wiki/Fraternity
Note that there's also things beyond academic fraternities (like Fraternal Order of Police?) which ... make my head ache.