That doesn't take into account the production footprint of a device capable to render today's web with all its transitions and glory, the environmental and geo-political toll on extracting lithium, rare earths, and other materials, plus the footprint of delivering devices into the hands of users, and disposal after typically only two years of usage.

Whereas had we been sticking to deliver just plain passive HTML markup users are after, we could've had solar-/light-powered devices with slow LCD displays and low-power RF transmission similar to old e-book readers by now (solar-powered pocket calculators were available in the 1970s already).

Would help with tracking, privacy, ad monopolies, and browser obsolescence as well.