That's interesting. Never really thought about it before.

The Internet says a typical modern spark plug has around 500 to 3000 ohms. 500 ohms new and increases as it ages.
Modern spark plug wires have between 10,000 to 12,000 ohms (typically).
A solid copper or aluminum core wire would have a few ohms or less.
So a lot less resistance (500 ohms versus 10,500 ohms for example) means a lot higher current through the parts along it's pathway.
It takes voltage to fire a spark plug (around 3000 volts).
It takes voltage to jump the gap from the rotor button to each cap electrode.
So the increased current (more than needed) would negatively affect the parts that move and parts that arc, more than the others.
The other parts would have to dissipate more heat.

I think Jerry's statement has some merit.

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."