Unfair losses

Short and simple. Why can't you implement a loss prevented system for if one of the players is level 1 by the end of the game. It was a 4v5 since the very beginning. It doesn't happen often, but when it does, you just think.. Do I really deserve to lose LP because one of my teammates never connected? Is that fair? Is it that hard to implement a system like that? We don't actively choose to play in 4v5 games. We come into a game expecting a 5v5 and if we lose or win, it doesn't matter. But when I lose LP because of this unfair reason, it disappoints me. What drawbacks is there for implementing a system like this? Giving a loss prevented to a team who's player never connected at the beginning is completely fair. I'm open to listening to other people's opinions even if goes against my own. If there are drawbacks, I would like to know what they are.

Edit: The one who never connected, whatever reason it may be, should still lose LP, but the rest of the team that was forced to play and most likely ff at 20 should get the loss prevented.