The title above is a position held by many. It is not a position held by me. Saying that, I don’t think it is a position that comes out of nowhere. It captures a general concept, and comes some way in delimiting computer games from other non-linear electronic interactive media.
If TotalBiscuit did not create the popular idea that games need, amongst other things, a lose condition, but from some of his videos it is clear that he’s trying to describe the concept, rather than a prescriptive description. It might be the case that everything he calls a game technically has a lose condition, but what doesn’t have something that be cajoled it into being a lose condition?
Reading a book includes the physical challenge of turning pages in order to get to the end. While in Wario Land Three there is, unless I’ve forgotten*, nothing to throw you out of a level. Indeed, it is eminently possible to fail due to knowing what level to enter next, since discovering knew tools allows the travailing of previously locked areas of previously visited levels. If you fail to continue it is only through you as a player giving up.
Saying that a lose condition could easily be thought up. In games like Dark Souls where your death is literally necessary to survive (‘Dragon’ said as a reminder to those who know) one could easily make up the lose condition of not dying anymore often than is literally necessary. However, that is not actually in the game.
When you get to vague rules that can be legalistcly bended to include rules you get very close to what I’d define a game to be: Something sensible trusted people would agree to be a game. It isn’t a definition that lends itself to blogposts.
* I just looked at the wikipedia page, and apparently you can die to the final boss. However, I think we can all agree that the final boss wasn’t the decider of whether Wario Land three is or isn’t a game.