I have been fixing cars since 1974, and now teach others to fix cars. Oil formulation changes were a direct result of emission devices. http://www.enginebuildermag.com/2012/03/zddp-when-where-what-why-how/

Do a search of new engine designs after 1995, I think the majority have roller lifters, they are more expensive, but they don't require the high load oil additives like ZDP. Diesels after 2006 are supposed to use different oils as well, guess what they have catalitic converters. Nobody forced oil companies to change formulations, but if you don't, what cars can they sell oil for? The current API standards do not meet any of the OEM standards for oil formulations for new engines, I do not use any oil that does not say it meets the OEM oil standard of the vehicle I am working on. so it is really buyer beware. Bad thing is using the wrong oil does not show up right away, it takes time to wear out your engine.
http://www.enginebuildermag.com/2014/03/choosing-right-oil/