It's like everyone forgot that this isn't new; Apple already did it in 2019 with their Cheese Grater Mac Pro, with a second pure-power PCIe connector, and ASUS has also been experimenting with similar back with their Utopia Prime concept that hoped to cut down on cable clutter by just embedding the power connections into the motherboard.
Sure, I wouldn't trust ASUS with power delivery consistency given their recent issues that GN pointed out, but the idea itself again is not new, and has been proven in at least one instance, even if it's a niche one (outside of regular servers, which I'm told does also use a similar power delivery setup but integrated into mezzanine riser/daughter boards).
If anything, it'd be a good idea for AIB GPU makers and board partners to add, removing the risk of fire at the pinouts (esp. with Nvidia's pointless connector). The issue then is more about dealing with sag, and preventing GPUs from damaging the slots.