All engine oils have to have zinc or they can’t be classified as engine oils.
And zinc dialkyldithiophosphate (thats really what it is...it’s not just zinc because without the other components the zinc wouldn’t do anything) used in an engine oil affects what other components and how much of those components you can use.
As I said earlier too little zinc will not only be hard in the cam lobes but it’s also a ring killer. The compression ring is lubed mostly by dry film lubrication, and that’s the ZDDP. Too little and you lose ring seal (the base oil and additive package also affect ring seal but ZDDP is a big part of compression ring seal) and get accelerated ring wear. Too much and you lose power and it changes how you build the oil relative to what additives and how much of those additives you can use.
Oil is a science. You can find not only power in oils but you can extend the life of parts that are under extreme duress. Like the top rings, valve guides, valve springs, pushrod cups and adjusters and things like that.