Doing something like a Project with History isn’t of much use if the input gets deleted. I would guess this might not be a great idea if you have History enabled permanently, but that’s not currently recommended anyhow.
That idea makes sense even if History is always on. History could just change the Deleteinput default. Like this you can still set it manually to Deleteinput=Yes if you like.
Maybe the # in front of a history command could suppress the Deleteinput option altogether and set it to No anyway.
In any case a warning is at it’s place.
Basically this is shortcut to deleting a History parent, that should be noted to the user.