If you have ever been racing a bike and had a front spocket come loose you would be in no doubt as to why they are used. they are a necessary item for safety just like split pins on brake torque arms, axles, and footrest pins. I have a 16 stitch scar that reminds me EVERY time I ride that such things are important to fit and ensure are still present before riding/racing. A good scrutineer won't let you start without one.