Let me start by saying I'm not here to burn any bridges and I have no problems with anybody...
I have to agree with Korn here.
I added these exact capacitors to my Gottlieb Volcano (sys80) per the advice of Ed at Great Plains Electronics to prevent switch arcing that was absolutely KILLING my switches. The arcing was really, really bad. We're talking blue streaks of lightning here
I put these exact caps on the kickers and slings and never saw another arc again.
Using capacitors to prevent switch arcing is well documented. It's mentioned in Clay's guides and in several topics on RGP. I've never heard of them being needed or used for anything else.
Some good info on switch arcing here. Turns out adding a capacitor in this case is called "condenser", and the circuit it makes is called a "snubber" circuit. I'm assuming the coil takes the place of the resistor in the circuit outlined in the link below.