Same why no one (except maybe disabled people or totally technically clueless ones) would need an LLM to toggle HDR or adjust brightness/volume/whatever.
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ok, bad example as i actually do that in a smart-home
Having copilot built in to windows is basically "smart-home"-ing your computer. No one needs to ask home assistant to turn off their lights, but it damn sure is handy and most often faster than doing it manually - same with my example of turning HDR on/off.
Having it built in means you could ask it to interact with every piece of your computer. If you can't see how there is no USE for this, you've got a very narrow mind and no ability to think outside the box.