Or, for our specific purposes, why would I need an expensive device with higher-powered CPU if the sites and applications run well on a lower-powered device? P

Or, for our specific purposes, why would I need an expensive device with higher-powered CPU if the sites and applications run well on a lower-powered device? Precisely that. We need more human work (optimizing code) and less brainless energy spending, i.e. more jobs and less consumption of non-renewable resources.