Good thread to bring up.
I don't have any inside information, but I think disfellowshipping was 'on the books' previous to '52, but seldom used in the US. I would guess that part of the reason disfellowshipping took off was the post war expansion which brought different needs and the organization didn't have a way to control it. Gilead started in the late '40's and they started to have conversions of a lot of different backgrounds from the various countries they sent missionaries to. Polygamy, voodoo, you name it. They got themselves trapped into the practice of ruling on disfellowshipping matters that they would have been better not commenting on or making rules about.