Private clouds offer "none of the benefits" of a robust public cloud, and are only a stopgap solution perpetuated by "old-guard" IT companies such as IBM, said Andy Jassy, Amazon senior vice president who heads up Amazon Web Services. "If you're not planning on using the public cloud in some significant fashion, you will be at a significant competitive disadvantage," Jassy told a packed auditorium of nearly 9,000 IT pros Wednesday in Las Vegas, for the opening keynote of the AWS Reinvent conference.