On an old fashioned system such as the standard one, the distributor cap and rotor arm introduce an extra air gap into the system that we lose a lot of spark power through. Wasted spark keeps that voltage intact right to the spark plug.

It also gives us extra coil charge time at high revs as the coil has far less work to do per crank rotation due to the wasted spark configuration. This translates to better sparks.

Also, the mere fact we got rid of the distributor cap, rotor arm and the old king lead makes the system far more reliable too and much much less susceptible to damp problems.

It will also usually pick up some horsepower too, so winner winner.