Currently KWin still supports destructive window shortcuts like "Close window". That's a problem, an admin might have enabled it or changed the default shortcut for all users because it's so obvious to the admin but unexpected to users. Then a user might accidentely close one of its windows and lose data because they used the wrong shortcut. 

Therefore I suggest to remove all destructive shortcuts in KWin in order to make it more user friendly and to have a predictable user interface with explicit and clear destructive actions.

STEPS TO REPRODUCE
1. Change the default shortcut for "Close window" from <Alt><F4> to something like <Ctrl><Shift><Esc>
2. Ask an experience Windows user to open the task manager on Plasma
3. The Windows user might use the shortcut <Ctrl><Shift><Esc>, which opens the task manager on Windows

OBSERVED RESULT
The task manager doesn't open but the currently focused window gets closed and the user might lose data.

EXPECTED RESULT
The window shouldn't close because someone hit the wrong shortcut.