I don't know anything about CPU optimisation, but it makes sense that likely 90% of the games if not more were built using Intel systems.
A few years ago i would have agreed, but with amd getting into consoles and ryzen is appaerntly going tobe in the new consoles aswell as the current gen then that changes things dramatically.
Simply because most pc games are built for console and then ported over, then i dont see how developers would go for intel over amd when it would damage the console games aswell.