I heard Hal Varian say this at Berkeley a few months before he left it as a comment here:
But hereâ€™s another angle on Mooreâ€™s Law: it is to some degree a coordination device. A computer system involves CPU, memory, disk, display, etc., and all the components have to improve at the rate to avoid a bottleneck. The system is only as powerful as its weakest link. If the semiconductor industry tries to double the performance every 2 years, then the disk, RAM, screens, etc can design to that benchmark. By this view, Mooreâ€™s law could be 2 years, or 3 years, or whatever â€”- what matters is the common expectation for component parts manufacture.