If you spend some time on speed talk with the guys with many many years of engineering behind them and then if you look at what it takes pressure/friction wise to get zinc to actually come into play as zinc only becomes active after a certain amount of friction is created and with stock parts you dont get to that point if things are working properly
Some say zinc, some say material, I use only old stuff from the 80-s even have my cams reground on old 80-s core with new profiles and use a very minimal amount zinc additive. Along with other factors that wipe cams I guess im the only guy I know whos never lost a cam.
I run off the shelf rotella and 2 oz of comp zinc additive on our bracket car modern coated bearings. I think there is more hype and disinformation, selling $12 a quart oil, and people fucking up there installs and break ins and alot of bad cam deals get the "Lack of zinc" excuse. But install errors was still present in the 70s, but more just admitted they messed up. They only cams I ever wiped were factory ones in the 70s with good off the shelf oil because of poor maintenance and over 50 k miles.
Remember when our old cars were new, they were eating t chains at 40k miles, cam and lifters at 60k (they had plenty of zinc then) and really think back to the 70-s if a car had over 65k miles, we looked else wear because it was on the downhill slide. Remember spark plugs every 30k miles, trans services, rad flushes.... ball joints every few years, none of that applies or is even on the same level today.
But we all do what we do, I dont care if people spend 100 on an oil change, help the pope, or even if they traffic new born children, we all do what works for us.