If my (limited) understanding of electronics is correct, when a diode or ceramic disc cap is placed on a playfield switch, the rational for doing that is to stop any reverse voltage and bouncing which could cause erroneous issues with the switch matrix, yes? The diode does this by restricting current to one direction and the cap does this by essentially cancelling out any reverse current. Both accomplish the same goal but in different ways. If that is correct, then why do some systems use diodes (e.g. Williams) and others use disc capacitors (e.g. Bally)?

Not that there would be any sane reason to try this, but would swapping out a disc cap for a diode (or vice versa) work?

My understanding was incorrect. That said would a symptom of a missing diode be a missed switch closure, phantom closures on other switches in that row/column, or both?