No way. You'll never remember which thing you last set to silent or too loud and next time it'll come out surprisingly wrong. You might not know which window is

No way. You'll never remember which thing you last set to silent or too loud and next time it'll come out surprisingly wrong. You might not know which window is in focus, and it might not be the one playing the sound. If you do accidentally turn up, say your web browser while trying to adjust your media player, you'll never know how much too loud it will be until next time some autoplaying video starts. It would be a frustrating mess. Just change the volume when you turn the knob without any stupid computer logic trying to get in your way.