AFAIK KDE is not a display manager.
But if your desktop goes completely dark when tuning the light slider all the way down, you wouldn’t be able to see anything, and how then would you turn it up again? If you don’t have an alternative way to regulate than the slider KDE provides.
Seems like a decent precaution to me, if you really want it all black there are other ways, like turning off your monitor, or just use powersaving, or use a black screensaver. Alternatively you can make an app in a few seconds in for instance Lazarus, that goes full screen black. And would be easy to close again when you want the picture back.The brightness on a TV or monitor doesn’t go to all black either. IDK if it’s a coincidence, but my monitor adjustment, and adjustment in KDE look identical when I have one at 100% and the other all the way down.
But if your desktop goes completely dark when tuning the light slider all the way down, you wouldn’t be able to see anything, and how then would you turn it up again?
I did it in school computer class once with display controls, the controls were affected by display settings, so when I set it to 0 brightness and 0 contrast and left the menu, there was no way to tell what are you doing.
The IT person used a neighbouring monitor to navigate the menu and replicate all the actions on a dim monitor, they were a bit pissed but I guess they also saw it as at least a bit funny
