I thought the section heading "Why is the coil the secret sauce?" seemed very dubious (as is acknowledged), but it's been long enough since I've done electronic

I thought the section heading "Why is the coil the secret sauce?" seemed very dubious (as is acknowledged), but it's been long enough since I've done electronics that I can't contradict it in any way. But an analysis that focuses on the very low resistance of the wire and ignores the back EMF from moving the pendulum seems wrong.