It does not work like that. Banishing light says that the permanent is exiled until BL leaves the battlefield. When you concede in a multiplayer game, all your cards you own are removed from the game and the exiled permanent will return to play.
February 29, 2016 7:57 a.m.
Banishing Light does not permanently exile things when you concede but Oblivion Ring does. Notice the slight difference in wording. Most of the time if someone does what I like to call the "dick move" and exiles stuff just to mess with people and concede my playgroup just returns the stuff because although it isn't technically how the rules work it returns the game to a playable state after the person who wasn't trying to win leaves.
February 29, 2016 8:34 a.m.
Notice that Oblivion Ring has two separate triggered abilities. One for when it enters the battlefield, and another for when it leaves. A player who's out of the game can't put any spells or abilities onto the stack, so when a player with an Oblivion Ring leaves the game that means Ring's "leaves the battlefield" trigger can't be put onto the stack when it goes away. The exiled card doesn't get returned to the battlefield.
Banishing Light, rather, sets up a zone change with a specified duration, namely "until Banishing Light leaves the battlefield". When a player with a Banishing Light leaves the game the duration of Light's effect simply ends when it goes away. The exiled card does get returned to the battlefield.