Let your left wrist do whatever it wants or needs to do past impact. It doesn't matter at all.
That sums it up for me. Hogan had a bowed left wrist at impact, yet he hit hard with the right hand.
He said the left hand has no role to play in a golf swing, apart from NOT BREAKING DOWN AT IMPACT. After impact,you can wrap it round your head like Daly or pose nonchalently like Els,it doesn't matter.
However, Harvey Penick and others were/are grea believers i getting into the impact position and working bacwards, therefore an undertsanding of what is happening is desired.
Personally, I think the problem stems way before impact, power is lost because the release is to early. A pro can deal with this, Watson had an early release, Hogan late, Nicklaus somewhere in the middle. I just don't think there is one position that suits all. What is desired is too time the head square at impact, the left wrist isn't the solution imo, its sympton.