Thought I'd add to the "fray"
Whether you splice or knot your docklines in order to make a loop to pass it around a piling, a lot of wear is going to occur where the bitter end passes thru the end of the loop, be that a spliced loop or knotted loop. And you'll increase the liklihood of dockline failure if the bitter end coming out of the loop around the piling does not run fair to the cleat on your boat.
Whether you splice or knot your docklines in order to make a loop to pass it around a piling, a lot of wear is going to occur where the bitter end passes thru the end of the loop, be that a spliced loop or knotted loop. And you'll increase the liklihood of dockline failure if the bitter end coming out of the loop around the piling does not run fair to the cleat on your boat.