The big reason for less wear, the LEAD was taken out of gas. You oldtimers remember how bad the plugs looked after 15,000 miles. Today they go 100,000. The lead ate up cylinder walls and exhaust pipes in no time, very corrosive.
That's an argument I've not heard. The lead was introduced for cooling and lubricating purposes, I do KNOW that. That's why we got hardened valve seats and stellite faced valves after the reduction and elimination of lead from gasoline.
All of the health reasons are all I've ever heard about why lead was removed. I'll not argue because I don't know of any other reasons.
