What happened to this character creating this phenomenom?
(spoilers for DIO's Diary, Vento Aureo, Phantom Blood, and StarDust Crusaders)
Joseph never said that the stands were created or summoned directly through DIO's awakening, however he did say that ONLY the Joestar bloodline's stands stemmed from him, as he is indirectly a part of it by stealing Jonathan's body, in DIO's Diary: OverHeaven, he explains that when he awakened from his 100 year sleep, he met Enya, who shot him with the arrow, thus giving him, Joseph, Jotaro, and Holly stands. Everything that was said in Vento Aureo and Diamond is Unbreakable, is true, and stands never stemmed directly from DIO or Jonathan.