Well yuh, but in general when you put things together they are linked by hard lumpy and dirty chunks of metal which if they fail have a tendancy to make really expensive sounding noises making it easy to diagnose or possible nothing at all moves making it even easier yet.
I have seen very few intermittent timing problems that were not electronic in nature or the assembly of those lumpy pieces done back asswards.

I order to have proper "good" compression the "hard lumpy" stuff has to be right/in good working order. That being said, I agree, electronic/ electrics is the most common fault source. and the timing for a DIS system is ALL "electronic" with the exeption of the sensor and wires, which are part of the HARD stuff.