Why can't Riot tell when someone has sat at base all or most of the game?

I feel like this should be an easy thing for the game to be able to recognize and then not penalize your team.. whether it's dc's or trolls, shouldn't the game say "ok, this was a 4v5 - that character model was at the fountain for X amount of the game" and then not award negative points for a loss? I don't care if the winners get points for winning but losing points for that garbage is insane.. it's a not a hard thing to implement.