Who's band when they change their sound so much they basically fall into obscurity after Ozzy leaves?
Dio was a shit front man and his presence lost fans immediately. That they hung in for three more albums was valiant but pointless. Dragging out the death of the band over the next several decades because their sound was so good without Ozzy.
And had Charlie "fired" Mick, the same fate would have befallen the rolling stones as did Sabbath. You could have all sound you want yet without the charisma you had nothing.