User blog comment:SpamCrackers/Jojo's Bizarre Language Adaption/@comment-4110939-20151015062257

I think the point was that the narrator was meant to sound like one you'd hear in dubbed anime from the 90's (i.e. DBZ original dub and such). As in the narrator voice is so clonky and corny it actually works, which ties in to JJBA's age. It's safe to assume the original narrator sounds just as corny for the Japanese, likely giving off a similar vibe in tone.