I feel like we are kinda comparing apples to oranges. I went to a school where joining a sorority gave you NO additional social standing, in fact, if anything, it knocked you down a few tiers. (Though everyone would attend our parties

) At the 'southern' schools, there seems to be a social tier benefit to joining, it is more like a business move than necessarily a social move.
We took women who were called skanks, but so did all the other groups. We took women who graduated virgins, so did all the other groups. I went to a school with one NPC and two locals, no defined quota, no rush rules except deffered till spring. In all honestly, if we wanted to defy national and serve alcohol to our rushees and have boys over we probably would have been able to get away with it. Water teas are another planet.
I still think our founders never envisioned SEC style rush, however, we are a long way from grabbing freshman and running them from the train/bus to the house to be pinned.