The general design was introduced on the ‘23. Here’s my take: with the changes introduced, the turnbuckle design allows for a greater degree of RC/camber change on the outside of the rear arms, by way of the small link mount plate that installs onto the hub. This allows for a level of adjustment that could not have been made with the previous pillow ball design. Sure, they could have applied this to the front as well, but I would venture to guess that a) this might affect durability/geometry up front, since that hub also has to pivot on the vertical axis for steering, and b) perhaps team drivers are happy with the adjustability they have up front, and needed more in the rear. I mean, if it ain’t broke, why fix it?