I think it may have to do with the fact that diploma programs don't include a degree. Nursing , in its progression to want to be taken more seriously has gotten universities to teach nursing rather than hospitals`, which is where diploma nursing originated from. Back in the day, nurses typically only got diplomas to become RN's. My mother was a diploma nurse and graduated in 1958.

As time marched on however, it became more apparant that a college degree was more appropriate than a diploma. I guess it raised nursings status to be affiliated with a college. Eventually, diploma programs phased out. I lived innew Orleans, and Charity hospital was still running a diploma progam up until 1992. They then merged with Delgado community college to have an AD program. It seemed to make sense, and ended up being about 3 years(same as diploma) to get an AD RN.