This is incorrect technique for PLing.
I could not find the Leeman or Hedlesky videos on Hook Grip.
I think the reason that PLers are stuck in this incorrect Hook Technique for Powerlifting is because it is correct for Olympic Lifting.
But the sports are very different. Even Deadlift form is different for Oly Lifters.
Here is why Hook for PLing is different:
In Olympic lifting they must have much greater control over the bar. They lift it, pretty much fling it and then have to maintain enough control over it to catch the weight. Having the bar deep into your palm with your thumb wedged in there keeps the bar as controlled as possible.
In Powerlifting all we are doing is lifting the bar and setting it back down. This requires significantly less control over the bar.
Another factor is that Olympic lifters are using significantly less weight than Powerlifters. They may be applying more force but I dont know the physics so for right now I will say that with more weight the pain of hook grip is amplified.
Even if more force is applied in an Olympic lift in Powerlifting it is not necessary to feel that same pain that comes with their Technique. As it so happens due to the arm length differences it is also sub optimal to use their Technique for Powerlifting.
EDIT: WORTH MENTIONING: Olympic Lifters tend to use much wider grips so the hand angle will cause the thumb to more naturally dig deeper into the palm. Powerlifting hand angles means that you must do more work to force the thumb into the palm and this will make it more painful.