Here where I work as a tech writer, there's a system in dev with a field on a screen which is a drop-down menu, and the selection defaults to "none". At that point a certain feature is turned off. If you select anything but "none" the feature turns on. For that feature to work, either or both of 2 other fields need non-0 values, and they are set to 0 to start. There's a note on the screen that says to check them. I take the view that the system should prevent the "non-none" choice from the drop-down being accepted if neither of the other values is non-0.
We do know that computers are good at that stuff... 5 minutes coding to do a check, and no calls to the support desk...
My boss agreed and took that view to a meeting. Meeting says no, not a bug, explain in the manual.
Oh well, it pays the rent.