To this point in the 3.75" line, we have a small number of figures with lightsaber hooks sculpted onto their belts. One such example was the recent "Jedi Master" Luke from TBS/TVC. However, that feature has always been ornamental and not functional (to the best of my aging memory). To actually attach the saber hilt to the belt, the familiar "hilt peg to belt hole" pattern was used. It worked, but sacrificed aesthetics some. In the 6" scale, the saber hilts have been sculpted with a loop that allows them to attach to the belt hooks as you can see on the TBS Bespin Luke Skywalker. As of the reveal of the upcoming TVC Luke Skywalker (Crait) figure, it appears this 6" feature has been migrated to the 3.75" line. Add it to the growing list of such features, to go along with Photo Real and upper thigh swivels.
The culmination of all these formerly 6" exclusive features being ported over to the 3.75" scale leads to only one logical conclusion. Hasbro had simply created the 6" line for experimenting and testing the viability of new features to be ultimately be used in the 3.75" line, and is clearly now gearing up to drop the 6" scale altogether in favor of the one true scale.