Once-upon-a-time a "bright" bulb consumed 80W of power. Today we achieve the same light output with 8W of LEDs, and order of magnitude decrease in power consumption. Multiply that by every home, every street light, every office build, every airport, hospital and stadium. That kinda improvement in efficiency adds up very quickly.

Sure plenty of developed countries have deindustrialised, but most the heavy industry that been lost was lost before mass electrification. Arc furnaces, large scale aluminium production etc. These are all pretty modern technologies. If you look at the UK the only major steel foundry left is a gas fired blast furnace, we basically have zero arc furnaces, because we deindustrialised before the damn things we're being used for large scale steel production.

Electrification of heavy industry is a surprisingly recent trend, and is only really happening in countries that aren't deindustrialising, and view continual process improvement in heavy industry as an important long term activity.