But that's not the case, in an engine designed for Dexcool, baring other problems like an EGR cooler in a Ford Powerstroke, or a fitting that cracks on a 3800.
Yes, those new materials you listed (except iron). Green silicated wasn't the greatest with aluminum. Radiators used to be brass/copper, and engines had much less aluminum than they due now. Also there's more plastic. Even alloys have changed.... compacted iron? Magnesium with the aluminum (I know BMW did that).
Running straight water is a terrible idea, outside of maybe a race situation, where the next 500 laps is what matters. Old cars like Model Ts didn't run as long or hard as a modern engines.