Well, in some sense what happens with “smart“ indentation features in editors is anything but consistent (I know I'm not talking about the same consistency here

Well, in some sense what happens with “smart“ indentation features in editors is anything but consistent (I know I'm not talking about the same consistency here), because they only ever make an exception for the backspace key to remove N spaces – in some cases. An arrow key only ever moves one space at a time and a delete doesn't ever remove N spaces and you can still land in the middle of an indentation level either with arrow keys or with your mouse cursor, etc.. And to make matters worse, the way the backspace key works isn't even always what you want; say you try to align something and happen to press space one time too many: in many editors pressing a backspace there doesn't fix your problem but only makes it worse...