The official justification is that the only place cards enter to is the battlefield, so it’s unambiguous. Cards can still leave from a variety of places, so it’s still necessary to say from where.

I think I figured it out. The battlefield is the only zone a permanent can enter into. In other zones it is put in, like graveyard or command zone. They can’t go with leaves alone because it would imply a trigger in the graveyard or exile.

So this way it actually makes sense. Still sounds fucking stupid tho.

Yeah, kind of. It’s because of the “return” effect being a separate triggered ability, which has some odd rules interactions.

It’s a bit before my time, but I think Banishing Light was created specifically to be a more accurately-worded Oblivion Ring that avoids rules quirks.