It can uncleat itself in this fashion. It can get caught on something in the water. It slows the boat down. It puts the sheet out of reach of the skipper in the case he needs to blow it.
I could name others. Did I pass?
Rick has always held his own mainsheet, but my job as crew was to make sure the sheet stayed on deck. He explained to me that the reason he gets so frantic when the sheet washes out the back is that the pressure can be so great (water pulling the sheet) that he would not be able to release the mainsheet and let it out, if necessary.
