If this sounds like your week
Changing brightness shouldn't mean leaving your game or alt-tabbing away.
You're mid-match or deep in a fullscreen app and the screen is too bright. To fix it you'd have to break focus, reach for the bezel, or dig through a menu — none of which you can do without losing the moment. Windows offers no keyboard shortcut that touches an external display.
Where tooling usually breaks
Breaking flow to dim a panel is its own small tax.
Every interruption — minimise, adjust, restore — costs concentration, and on a multi-screen rig you often want only one panel nudged, not all of them. There's simply no built-in chord for "make this display two notches darker right now."