all these 22+ inch claims are dubious, and sure, not everyman is created equal, someone can be "small" and yet have an outstanding bodypart.
but the thing everyone keeps overlooking is the evolutionof seo's (synthol). Darrem Charles for example, always had great arms with peaks, very good bodypart, but although he did not increase his weight by much throughout his career, his arms grew significantly, through intellegent, precise and methodical, consistent use of seo's.
Like many other pros with outstanding, extremely developed arms. Priest, Flex, Jay, Kevin, etc
So, yes, there has been that evolution since Arnold and Sergio's day.