Wes,

Most sailboats were built with an over-hang stern, for reserve buoyancy
in a following sea, which didn't have much transom.

That was in the days of wooden construction. With fibre glass hulls it
has changed, some, but still an awful lot of sailboats are built with
narrow, high sterns. That lets them squat on the stern wave to keep the
hull flat and the rig upright.

It is changing some. My boat has a closed stern/ swim step stern but
below the water line is a bustle canoe shaped hull. I love it but I'm an
old man and the "Blue water" days are well behind me.

Ole Thom