I don't know what pictures you saw this in, but have you considered that the boats in those pictures may have been running their rigs with loose diamonds?



My feeling is that if they had pre-bent masts and were over-rotated, they were probably trying to increase power in light wind or serious chop.



The foil's effective draft is deeper when the mast is rotated further and this provides more lift.



The top portion of the mast above the hound will be in a position that will induce bend on its minor axis; this adds power as well.



Thirdly, the same top portion will be prevented from bending off or away on its minor axis, taking the leech to lee with it, and spilling off a lot of pressure. This prevention of sideways bend up there prevents the associated loss of power from spill-off.