Sort of a "belt and suspenders" situation- - - -if you're going to go to the effort to add an extra ground, it might as well be something that will work for quite a while. Ford distributors in the 1960's and 70's used a wire from the coil to the distributor that went all the way to the points. It had a nasty habit of breaking strands between the grommet that plugged into the housing and the points inside the insulation, and cause an intermittent stutter when the advance moved. We would diagnose it by disconnecting the vacuum line, and the stutter would go away. It was a common enough failure that I got into the habit of keeping a few of those wires in stock at the shop along with the points and condensers and other ignition parts my jobber stocked on consignment.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!