Guess its a bit like having a shock leader for beach fishing with a rod. Thick mono seens to last and last where as nylon has a fraction of the life, as its the first bit of the line that takes the wear and tear, it makes some sense to use a hard wearing material up front but once the spear is home in a absolutely humungus fish!! and it takes off, what you need is a flexible line on the reel to play the fish with I guess( no experience with this myself apart from one 50 yard tow from a Bass)