3 people on the team never loaded in (including myself) and it wasn't loss prevented?

Just played a ranked game where 3 out of 5 people on my team only never loaded into the game. I never realized that I wasn't loading in because the loading screen was moving along fine, I was at 100% and everyone else eventually got to 100% as well. After about 3 or 4 minutes though, I realized something was terribly wrong and had to restart the client. This of course takes forever because after pressing launch on my client nothing happens about 60% of the time so I need to try and restart again. Finally i get into the game, run off to my jungle to try and catch up and I get killed by a level 6 rek sai. 2 others on my team had the same issue but were able to load in just before me. All of our lanes were horribly behind and I had no way of every getting back into the game.

Somehow this game was not loss prevented? how is it possible that I lose 17 LP because riot's client crashes and just hangs there until the player realizes that nothing is happening and needs to reload the entire game?