Namaskaram ji ,
I do not understand why Osho says this , .....Puranas in Vedic culture are are considered to have historical basis , I think it is just that they often appear to be simple in form as if they were story telling , ....thus mistake has arrisen .
take for instance the Baghavata Purana which gives accounts of the incarnations of Visnu , some take these to be mythological but their basis is in extreme antiquity , we need to remember that these accounts have been handed down through countless generations , in the course of time these puranas have taken on mythalogical status as perhaps the content seems too fantastical to be actual , ...this perhaps happend gradualy as the accounts became embelished over the years due to genuine love which maginifies some aspects of the content , whilst on the other hand we must allow for the fact that accounts get distorted through lack of clear understanding and translation ,