The reason is obvious - more power hungry GPU fit well with more phases of power supply and this fit well with higher input voltage.Why? To move the conversion from the cheap PSU that you most likely will use for 10+ years and move it to the expensive GPU, make it more expensive, easy to break and on top of that for sure it will be replaced more often than the PSU
Look how many phases we have on decent mobos these days.
The same trend will come to power hungry add on boards sooner or later imho like GPU or NPU discrete accelerators.
Demanding and aware users will prefer silent - well designed- power section than couple bucks cheaper but noisy and less reliable.
Especially in case they have to spend grand or more to get the card.