They manufacture oil to an obsolete specification and many with collector cars actually want that specification. Many old cars wil have excess sludge broken loose by mdern detergents. By friend with a Babbitt beater stovebolt 6 in his old 49 chevy wants that kind of oil.
I used to buy oil manufactured to the SM specification for my old convertible when I still had it. I was glad to get it as the additives were compatible.with that engine.
They are not shady, but marketers that put on the shelf in convenience stores are. However, cars that are worn out driven by folks that typically buy oil in convenience stores are not likely to have their life shortened by that oil. It is far more important they have oil. The rank is some oil is better than no oil. Clean oil is better than dirty oil. Quality oil is better than poor oil.
Rod