If ever a storm "over-powers" the dunes, it will do as you say:
Instead of the waves reaching a point, and eroding DOWN (making a "cut" at a specified point/parallel), it will go over and back way into the dry dunes, merely pulling down sloshy soft stuff.
HOWEVER, there is still hope for those beaches: Because in the coming days, mother nature will often rob sand from the mid-beach zone, to fill in sand that's been eroded from the off-shore unseen zone. Mother nature re-contours her beach slopes in the coming days high and low tide cycles. So it might pay to check back a few days later, when such phenomenon occurs. The times when I have seen this play out, is when the subsequent days have still-respectable surf heights. Hence it if goes down to "placid calm" the very next day(s), the days-after effect is less pronounced.
JMHO. Good luck to you guys !