I don't think anybody's denying that revolutions happen. It's just that the number of technologies that actually turned out to be revolutionary are dwarfed by the number of things that looked revolutionary and then weren't. Remember when every television was definitely going to be using glasses-free 3D? People have actually built flying cars and robot butlers, yet the Jetsons is still largely wishful thinking. The Kinect actually shipped, yet today we play games mostly with handheld controllers. AI probably has at least some substance, but there's a non-zero amount of hype too. I don't think either extreme of outcome is a foregone conclusion.