Non-LD shafts definitely create more squirt, and more resulting net CB deflection with less shot speed, and many people are accustomed to aiming shots crooked to compensate for this because they have played with non-LD shafts for so long. And it can be difficult for these people to adjust to a non-LD shaft, where the CB heads closer to where you are aiming. But
if a player can be accurate and consistent with a non-LD shaft, there is certainly no reason to change.
LD shafts do offer slight advantages to the people who put in the time and effort to get accustomed to them, but an LD shaft is certainly not required to play at a high level.