Say you have a computational task you want to run. You can run that on a single server for 1 minute, and use 5 watt-hours of power. Or you can translate it to

Say you have a computational task you want to run. You can run that on a single server for 1 minute, and use 5 watt-hours of power. Or you can translate it to JavaScript and run it on 50 web browsers for a minute each, and use at least 50 watt-hours of power. That's what this would look like, since you lose so much to having to use JavaScript, not having a dedicated server-class CPU devoted to your task, and to overhead of transferring the data to/from the client. Heck, you'll waste a bunch of power just sending the code and data to clients that leave the page before sending back results, which means their slice of the work has to be run multiple times on multiple computers. Same end result, 10+ times more electricity used, through a combination of having to do much more work, and doing it on much less efficient hardware. Money down the drain, pollution in the air. In reality the math is even worse than that for most tasks. So, nobody's suggesting you fill homes with more PCs for some reason. The suggestion is to leave the PCs we already own alone, drawing a fraction of their maximum possible electric usage. If you're going to try to better utilize existing capacity, do it by buying spot instances on AWS for pennies per hour, because those machines will give you vastly more computation per watt. It would also be more power-efficient to add a brand new dedicated server to the data center for these tasks than to utilize visitor web browsers.