If you are making an economic (financial) argument for change like the original comment did, then yes, it should be visible positive effect.

Obviously not if you are doing for your own fun or just improving the state of art.

Eventually everything ends up pumping the same resources from the same earth. The billion devices pool their 1 cents saved into the same pool of fossil fuels and the same power plants.

You don't need the effect to be observable on an individual level

It's something that is worth an engineer's time