I recently learned Google Chrome does something similar with browser extensions[1]. You cannot[2] install .crx files that have not been published to the Chrome Web Store.
It doesn't need to be digital feedback. Imagine you could physically see the water from a shower filling into a column of water. Let's say 70 liters might reach 6 ft. If someone could see this and wanted to use less water, then they just need to keep their showers short enough that the water fills to the 60 liter mark, then the 40 liter mark, until they're happy with their efforts. No crypto currency. No telemetry.
[1] https://blog.chromium.org/2015/05/continuing-to-protect-chro...
[2] Unless you're using Linux or the enterprise version of the browser.