I think DWR46 hit it on the head. Modern oil is formulated for modern cars. If you're running a flat tappet engine there probably should be some zinc in the oil, whether it comes in the oil or you add it. Adding treatments to your oil changes the chemistry. I'm not putting many miles on my Stude so I change the oil once a season.
For what it's worth, I've watched the Youtube videos by The Motor Oil Geek. I found them interesting and informative regarding the oil stock and the additives in the formulations. In some cases additional oil additives can negate the effect of the additives the oil company puts in.
When I bought my Avanti, the seller had converted it to roller rockers and wrote an article about it in the 1992 winter/spring issue of AOAI magazine.
As far as swipes at governmental regulations, I sure wish they'd stop. How many people are still upset they took the lead out of gasoline? Maybe there's a reason kids are smarter today, just saying.